View Full Version : Engine Stalls after Radiator Replacement

02-25-2008, 09:17 PM

Recently my radiator sprung a leak. I pulled it out and took it to a couple of local radiator shops, and they both pointed out several corroded areas that were getting ready to spring as well, and the both agreed it was time to get a new radiator. Unfortunately I don't have $200.00 to sink into a new radiator, so I did some junkyard trolling and came up with ONE radiator in relatively good condition, with the transmission cooling lines on the passenger side like mine (I don't know why, but all the 2.8L A-Bodies I saw had the lines on the driver side, but were otherwise identical radiators). I gave it a reverse flushing, but there was a LOT of surface rust on the inside, and I installed it.

The very next day after that problem was solved, the engine stalled on me at a stop sign. It happened again at a red light. It happened again when I was shifting from park to reverse. Each time it did this, it started right back up, except for the forth time, again when shifting from park to reverse, and this time it took some two minutes before it would start up. There was no clicking or whirring or anything... you turned the key and everything just went quiet. I gave it some time, and it started right back up.

It reminds me of an old Pontiac Sunbird I had with a busted Torque Converter Clutch - but the TCC never caused it to shut down when shifting from park to reverse, it was always when slowing from a cruise to an idle. There is a spattering of what looks like fuel coming out of the engine, up near the top, which makes me suspect maybe a vacuum leak or a torn gasket, but I'm no mechanic, so I don't know for sure...

Looking over the cooling system, I've noticed two things:

1) The radiator cap is a little worn out.
2) The reservoir cap doesn't fit snugly, and the radiator NEVER draws from the radiator, even when it was empty.

Just things I thought I'd note.

Also, I didn't think about it at the time, but I didn't flush the ports where the transmission fluids go to cool. I've heard that prssure problems in the transmission lines can trigger problems with the TCC, but I don't know for sure.

Any ideas?

02-25-2008, 10:47 PM
Take the overflow pressure hose that leads to the reservoir tank off the radiator and blow through it. If it allows air to pass, then fine. If not, remove the other end of it from the reservoir and find out if the hose is blocked or if the reservoir is blocked.

If all is clear, open the radiator cap attach the overflow hose to the radiator and blow air through it. If air passes, it's most definitely the radiator cap that has gone bad. I'm using a 10lbs pressure cap (2.8L engine) but I'm sure I'd do better with a 9lbs one. Until now I have constantly forgotten it. The one I have I bought new when I changed the radiator last June.

The stalling doesn't sound as if it has got anything to do with you chaning the radiator.... unless if you may have moved some badly connected wires while working on the car?

02-25-2008, 10:52 PM
Thanks! Regardless, I know the radiator cap needs replacing. Mine came with a 14 lbs. one though - is that too much?

Shot in the dark.... this doesn't have anything to do with my stalling problem, does it?

02-25-2008, 11:19 PM
The TCC will NOT cause the vehicle to stall, not from going from park to reverse. This will only occur in situations where the TCC is engaged and sticks, IE doesn't disengage. Typically, if your speed was less than 50, it would not have engaged to begin with. This is not TCC or transmission related (I can say that with 90% accuracy) So I would rule out that it had anything at all to do with the radiator.

If it's fuel that you see, smell it to see if it actually is. Obviously if it is fuel stop driving and correct it to avoid fire/death/damage.

To check for vacuum leaks, run the motor and listen (or use a length of rubber hose with one end at your ear and move the other around vacuum lines and associated connectors)

Secondly, you may leave the car overnight with the climate control in the off position. in the morning, before starting, slide the lever over to vent. You should hear a hiss (this is the door actuator moving) indicating there is still vacuum left in the reserve. If there isn't, it has a leak, big or small. These are the best places to start with.

Oh, also, when its not starting, that two minutes today.. How'd it sound? Like it was firing but not on all cylinders? Ex: hit hit miss (starter slows) hit miss (starter slows) or just endless cranking with no sign of life? Will it do this cold, or only hot?

02-25-2008, 11:21 PM
Thanks! I'll try that tonight and update you guys. Does it matter if it's in the cold or hot position?

I tried smelling it, but it was too dry to tell right away. I'm keeping my eyes on it though, and checking for fresh residue. The spatter doesn't seem like oil though because it doesn't trickle down... it looks like something splashed then dried up right away.

When it didn't start, NOTHING would happen. There was no solenoid clicking, no whirring... I'd turn the key and everything would be dead silent. Funny, huh?

02-25-2008, 11:32 PM
Doesn't matter if it's in cold, but when I used this method it was in cold. Theoretically, it shouldn't matter since all that lever does is move a cable that's attached to a door.

The absolute no-start sounds funny.. Was there power during this? Lights still functional? If not, then theres a ground at the bottom of the radiator support that you may have budged (Look to see its there anyway)

Hopefully someone else can chime in, since it sounds like your having a couple seperate problems.

02-25-2008, 11:51 PM
Ahhh, the beauty of a project car... :)

There were still lights and power to everything, although I can't remember if everything went dark WHILE I was trying to start it, although I'll try again.

If there a ground under the radiator, it wouldn't hurt to check it out and see what condition it's in. Any clue exactly where it is, or should I just start following wires?

02-26-2008, 06:40 AM
Check the wiring on the starter. It's not far from the radiator, and you may have bumped into things there when changing the radiator. Maybe a loose nut or a bad cable shoe... Trace the wires from the starter as far as you can, and visually/physically verify their integrity.

02-26-2008, 03:16 PM
I ended up working until eight last night, and I didn't get an opportunity to check anything, but I will tonight. Thanks again for all the tips... loose wiring definitely sounds like a possibility.

Thanks for all the tips guys!

02-26-2008, 03:34 PM
Thanks! I'll try that tonight and update you guys. Does it matter if it's in the cold or hot position?

I tried smelling it, but it was too dry to tell right away. I'm keeping my eyes on it though, and checking for fresh residue. The spatter doesn't seem like oil though because it doesn't trickle down... it looks like something splashed then dried up right away.

When it didn't start, NOTHING would happen. There was no solenoid clicking, no whirring... I'd turn the key and everything would be dead silent. Funny, huh?

this car has a carb right?

if you dont hear you starter working then you need to get that checked (battery, then wireing to it, then the starter)

you can check the splatter buy wipping some of it on your fingur if it gas it should still smell like it ;)

02-26-2008, 03:36 PM
This is actually MPFI... it was only the once when I didn't hear the starter going, but that has crossed my mind. I figure if I can get this stalling issue buttoned up, and the starting problem happens again, it'll be time to check that out too... luckily, I have a little experience in changing out starters!

I've got my fingers crossed for loose ground wiring that's been knocked around by radiator swapping... I can hope, right? :)

02-26-2008, 04:06 PM
Hmmm... I have to admit that my problems sound similar to Pushrod_V6's:

"the car runs like absolute a$$... "Missing, hestiting off the line, inability to control idle speed (normally too low), stalling, etc." "...Well, one day I was talking about the car with another friend of mine and he asked me whether or not one of the ground wires was damaged.... Sure enough, I found one that wasn't attached just below the radiator cooling fan. As soon as I did that, VIOLA! Perfect."

02-26-2008, 04:22 PM
MPFI, look into OHM testing the fuel injectors. Those injectors seem to get bad with time. If you need to replace them, replace all 6 at the same time. Some place like this is your best bet:


Don't waste your time with fuel injector cleaning at oil change places, etc. They don't work. Trust me. I went through about 3 of those $60 cleaning services before I realized my injectors were flat out bad.

02-26-2008, 05:05 PM
The ground wire is a small perhaps 12 guage wire that is bolted to the radiator support. It is easiest to see from the bottom, but plainly visible from the top with the rad out. It is on the outboard side (closest to engine) It's roughly center with the grill (except down, obviously)

02-26-2008, 06:01 PM
If it is loose, should I disconnect the negative battery terminal before tightening it?

02-26-2008, 07:21 PM
I got to thinking about what I did when I went through the radiator and I remembered something... and this is going to make me sound retarded, so bear with me... I didn't COMPLETELY tighten the negative battery terminal. It was a front mount terminal, and I couldn't get to it with a wrench, so I started it with some needle-nose pliers, and forgot to finish tightening it with a wrench.

That could cause stalling and a totally quiet no-start, couldn't it? :uh:

02-26-2008, 10:45 PM
Yes (But not very likely, still a possibility, tighten it)

02-26-2008, 10:46 PM
And to the previous question, no you do not need to loosen the negative to tighten said ground.

02-27-2008, 03:38 PM
Okay, so I double checked the grounds, and everything looked nice and tight. The negative battery terminal WAS loose, so I borrowed a tiny 8mm wrench to get to it and tighten it properly. I double checked all the wiring I could get to, and everything looked fine (although the loom is rotting away), and I took it for an hour long drive last night and I took it to work this morning.

It did stall again last night, only once, as I started the car and was pulling away from a curb to a stop sign (only maybe fifteen feet); I braked and it stalled, but it wouldn't start until I realized I was STILL in drive, and when I returned it to park itstarted right back up (which leads me to believe that the last "no start" condition had to do with either the battery terminal, or another situation where I wasn't paying attention to where the shifter was).

Having it driven it more in the last twelve hours then I have since I got it, I've noticed a few things... it idles a little erratically, and when you put on the gas from an idle, it tends to go quiet before it gets louder (this is only for a moment... not even a second; it just quiets down then revs up). The exhaust smells... rich, for lack of a better word, but that may have to do with the fact that the oil hasn't been changed yet (and the previous owner couldn't remember the last time it was changed).

My plan of attack over the course of this week:

1) Vacuum check and new air filter.
2) Spark plug change (I haven't double checked there condition, but it couldn't hurt).
3) Oil filter change.
4) Add fuel detergent with my next fill-up.
5) See if it passes smog...

I've got pictures to share once I bring my camera in.

02-27-2008, 07:37 PM
Okay, so two of these relays were loose in their mounting brackets, so I tightened them up, but I doubt that this had anything to do with my problems; I'm just leaving them here for thoroughness:


Here is the leak I see. It doesn't smell like anything, even hot, but based on the pattern I'm concerned that it's gasoline, and that THIS is my vacuum leak:


Also have an oil leak... that's a gasket that'll need changing out:


Any thoughts?

02-27-2008, 10:29 PM
I doubt you have a vacuum leak from the plenum. That oil leak is fairly common, nothing to worry about.

I made this on another board. I think it will help you a lot:

Fixing a Vacuum Leak on the MPFI

You're going to use rubber lines instead of brittle plastic. You need to save a bit of the hard plastic lines. They're used as connectors between engine/sensors and the new vacuum line.


Unplug the middle vacuum line and the bigger line on the right. Break off a chunk from each. Bring those chunks to any auto parts store. Tell them you need replacement vacuum line for these two sizes. I would get about 6 feet or ~2m of the small one, and half a foot or about .2m of the big one.

So you got your parts!

Start with the line to the left. This runs to the Fuel Pressure Regulator under the plenum. It has a T fitting, which then branches to a random connector to change direction in back of engine, and then to the MAP sensor on the back of the engine. This was cracked for me. Instead of taking off my plenum to replace a vacuum line, I ran new line around the side of the engine. Just remember you need a tiny chunk of old hard line to connector the new line to the MAP sensor. Map sensor is on the back of the engine left side. Don't forget to pull out old line under plenum.

Now the middle line! This one controls your HVAC/cruise control.
I didn't run it exactly stock, but it gets the job done. Use some zip ties to make it look nice. It runs from the engine to the right side of the engine compartment. It hits a "check valve". This picture borrowed from Discostudd sums it up nicely!
(Borrowed from Discostudd)

The Vac ball is at the bottom driver side of the front bumper. It removes with two bolts. Take it off and check for cracks. A replacement is cheap at the JY or something.

The last line is the bigger one. It runs to the EGR? (someone correct me on this). Just do the same thing you did with the other two.

This is a hand drawn vacuum line map from Bossman429. Ignore the bottom turbo part :lol:

(Borrowed from Bossman429)

Good luck dude.

02-27-2008, 11:02 PM
Thanks! That's a big help!

02-27-2008, 11:05 PM
Exactly what I did with my Jeep Cherokee. It had vacuum leaks galore! Mostly cracked plastic, understandable since it is an 89. I used tiny hose clamps over the rubber parts that go over plastic. Probably unnesscary since that small of a leak wouldn't really make a difference, but I did it anyway.

02-28-2008, 02:16 AM
Exactly what I did with my Jeep Cherokee. It had vacuum leaks galore! Mostly cracked plastic, understandable since it is an 89. I used tiny hose clamps over the rubber parts that go over plastic. Probably unnesscary since that small of a leak wouldn't really make a difference, but I did it anyway.

Thats still a good idea!

02-28-2008, 06:05 PM
Well I did a vacuum line check with a length of hose to my ear, and I couldn't find any vacuum leaks... however, I tried the "open the vent after leaving it closed all night" trick, and I didn't hear a hiss either (although I was in a hurry this morning, and the door was open when I tried it, and the "key in ignition" chime was going). I'm going to try the soapy water trick tonight, and re-try the vent thing in the morning.

It hasn't stalled again, either yesterday or today, but I'm idling really low (500 rpm?), and I noticed when I gas up from a stop the idle drops to nearly nothing for a moment before going (at least at first... when I've had it going for fifteen or twenty minutes, it does a little better).

So if I don't find a vacuum leak tonight, any ideas on what should I check next?

02-29-2008, 03:15 AM
The effect you describe when step on the gas and hear it "get quiet before it revs up" is often called "bogging" or "hesitation."

It's caused by a lack of instant fuel delivery when you step on the gas. First thing to check is the fuel filter. If it is plugged, you will have a hesitation.

Another possibility is a bad throttle-position sensor. It can cause hesitation, stalling, and erratic idle.

Others may remember additional things to check but these will be a start!!

02-29-2008, 10:48 PM
Thanks for the tips. I'm being told to check my Idle Air Control valve as well, and I'm picking up a multimeter tonight just for that reason.

In better news, it hasn't stalled since Tuesday, at it seems to run better with every day I drive it! Still would like to get to the bottom of it though...

03-02-2008, 01:08 AM
So my IAC valve seems to work fine, and I still can't find any vacuum leaks... I haven't checked my fuel pressure yet, but I will... I took it to get my California Smog Test today, and it FAILED due to high NOx levels at 15MPH... everything else passed with flying colors, just that NOx level...

And then I found this at Autozone.com:

"The EGR system is used to reduce oxides of nitrogen (NOx) emission levels caused by high combustion chamber temperatures...Too much EGR flow at idle, cruise, or during cold operation may result in the engine stalling after cold start, the engine stalling at idle after deceleration, vehicle surge during cruise and rough idle. If the EGR valve is always open, the vehicle may not idle. Too little or no EGR flow allows combustion temperatures to get too high which could result in spark knock (detonation), engine overheating and/or emission test failure."

Is this my smoking gun? And if so, can anyone recommend a supplier cheaper than Autozone (who wants $189.99!)?

(Special thanks to my Dad for pointing me in the right direction, and who has previously been forced to work on four other A-Body cars in the last ten years...)

03-02-2008, 11:22 PM
I'm used to dealing with the 3300 used on the Cieras/centurys. Since it has no EGR, I ignored that as a possibility. In the interim, you could disconnect and plug the vacuum line to the EGR valve to see if it stops stalling. Be sure it isn't stuck either, move it with your finger (COLD ONLY!) or a pair of needlenose.

03-02-2008, 11:42 PM
Most of the time the EGR valve is only clogged with carbon, not actually "failed."

You could take it apart and clean the carbon deposits from the passages inside and ensure the moving parts are free. Also check the EGR exhaust passages in the exhaust manifold, supply tube, and intake manifold. They can clog up, too.

03-03-2008, 03:07 AM

Diagnosing Digital EGR Valves

And find out what shop manual says.

03-03-2008, 03:11 AM
Also check the EGR exhaust passages in the exhaust manifold, supply tube, and intake manifold. They can clog up, too.

Bingo.....use compressed air or a wire to check passages.

03-04-2008, 12:14 AM
You guys rock unbelievably. Thanks for the advise, and especially for the "Diagnosing EGR Valves" article. Looks like I've got my new project for the week!

03-09-2008, 06:25 PM
Alright, I finally had time to pull that EGR valve off my car and bench-test it. According to the guide Ciera gave me, the following Ohms readout should have been true:

Terminals A to B: 20 Ohms
Terminals A to C: 10-17 Ohms
Terminals A to D: 20-30 Ohms

Here's what I got:

Terminals A to B: 23 Ohms
Terminals A to C: 13 Ohms
Terminals A to D: 24 Ohms

So the last two terminals were perfectly within spec, and the first terminal was three Ohms over-spec. I can't see how three ohms would make a difference, but does anybody else have an opinion?

Anyways, my dad showed me how to jumper the terminals to a nine volt battery, but none of the solenoids were clicking... it was dead quiet. I took it home last night and sprayed the solenoid ports with some Throttle Body Cleaner (out of curiosity, does anybody know if there's a difference between Throttle Body Cleaner and Carburetor Cleaner? Or is it just a clever ploy to get me to buy two cans of the same thing?) and let it soak overnight. I double checked the center port, and there was no leakage, meaning that the pintle is seated correctly. This morning I gave it another spray, just for good measure.

Instead of using a 9-Volt battery, this time we jumped it with a power source set to 9-Volts (and used a multimeter to check that we WERE getting 9V out of the supply) and lo-and-behold, the solenoids are all clicking along perfectly! I don't know if the 9-Volt battery I was using was just to old to operate the solenoids, or if (more likely) all three solenoids were fouled up, and an overnight soak in cleaner freed them up. Either way, I have a working EGR valve in my hands. I'm putting it back in the car tonight, spending the week monitoring for erratic idling or stalling problems, and come next Saturday I'm going in for my emissions retest (assuming everything works correctly now).

I'll update to guys with the results after I've had a chance to put it in and then run it in for a few days. I find it amazing that neither the Haynes or the Chilton guide say ANYTHING about performing this test. The Haynes guide tells you to take it to a specialist, and the Chilton just has removal and installation.


One final thing: A couple of days ago my car stalled again. And I couldn't get it started again. It had the same "no response of any kind" effect when I turned the key.

And I realized that the car was still in drive.

When I put it in park, it started right back up. So the first no-start problem I had MIGHT have just been my own carelessness. Thought I'd share... :banghead:

EDIT: Quick question (and let me know if I'm over-thinking this)... Shouldn't I have EITHER a rough idle OR a high NOx emission? If I understand everything I've read correctly, when the EGR valve gets stuck in one position and is flooding my engine with exhaust, I should be getting a low idle and stalling conditions, but I should be getting low NOx readings because of the low combustion temperature. However, if the EGR valve is stuck in the other position, then there's absolutely no exhaust in my engine, and I should be getting a higher NOx emission, but I shouldn't be suffering from low idling (I should be getting knocking because it's burning so hot). I may be oversimplifying.... I've got a three-solenoid digital valve, and there's actually seven separate positions it could get stuck in... but doesn't it seem like if I've solved the low-idle/stall problem, I've exacerbated the NOx problem?

03-11-2008, 03:48 AM
Don't take this too seriously, but yeah I would agree it would either be rough idle or a high nox.

Does it ever stall cold? Or is this hot only stalling

03-11-2008, 04:26 AM
Terminals A to B: 23 Ohms

I would say it is within tolerance...

EGR valve gets stuck

If its stuck open...you get stalling..erratic idle situations.

I'm not current with today's EGR operation; years ago, when they first came out, the EGR only came on with acceleration conditions (when motor was upto temperature)...and if it did not work (GM motor), you got some pinging noise.

but I shouldn't be suffering from low idling (I should be getting knocking because it's burning so hot).

Knocking does not happen at idle conditions...its when motor is under loaded conditions, if EGR is not bringing exhaust gas to intake...remember, newer vehicles have knock sensors, so any pinging will bring about a change in timing, which elimates the pinging, but your fuel mileage will suffer. Hence, your knock sensor changes timing, and this reduces engine internal temperature.

03-11-2008, 04:32 AM
Saturday I'm going in for my emissions retest

I've never done one in my life, but I assume your vehicle is put on a "tread mill," or engine is rev'ed up?

It's when they increase the engine load is when they measure NOx, most likely...not at idle.

In any event, if the EGR is not functioning...you flunk the test....assuming the intake passage-way(s) are not plugged up with exhaust soot.

On 1986 Chev Caprice, I had to take off intake manifold to clean up passage-ways...they do get plugged up.

But, maybe its just your EGR valve...might take a look at junk yard vehicles, might find a newer one out there...

03-13-2008, 12:11 AM
CieraSL92: It actually only typically stalls cold.
85_Ciera: Yeah. they put you on a treadmill and take readings at 15mph and 25mph. Stupid California... :)


So before I could get the newly de-clogged and bench-tested EGR valve onto the car, I had to do something about the bolt that broke in the EGR Base, and the EGR Base Gasket I found out was missing. A trip to Auto Zone and a BIG pair of vise clamps later, and everything is working great. It's still has some MINOR idling issues, but not like before... no fear of stalling for the time being! Also, the car is QUIETER than it has ever been (a really good thing!). As I go through over the next few weeks and get all the intake/exhaust stuff cleaned out, I'm pretty sure most of it will clear up.

I'm taking my Emissions Retest on Saturday. I'll let you know how it works out!

Thanks again for all the help guys.

03-13-2008, 03:22 AM
I hear a combination of 3 issues here.

Lets start with the easy stuff. Does you check engine light work? When you turn the car on, just befor you start it, and all the lights on the dash are on, is the Check engine light on? If the check engine light does work, have you checked to see if it is storing soft codes? If the Check engine light isnt working, get it fixed.

Secondly, it sounds like he is having a fuel delivery issue. Like the fuel pump is low on pressure, or his fuel pressure regulator is going out, or his fuel injectors are going bad. These are things that will need to be checked after he has checked for his check engine light codes..

Thirdly, The passages in and around the EGR connection need to be cleaned. The ports where those 3 little vacume lines plug in needs to be taken off, then the IAC unscrewed, and unplugged, then remove the top plate to the throttle body. It has 5 T15 screws. Take that off, and clean out the passages with a pipe cleaner brush, and some carb cleaner.

When you took off the EGR, did you take the EGR spacer plate off too? The passages in the spacer plate, and going into the throttle body are a well known spot for the 3.1 to clog up. Mine was so clogged, I had to use a hammer and a punch to even make a hole. Followed by a chissel, and a copper headed toothbrush.

03-13-2008, 06:12 PM
My check Engine Light DOES work, but it was only brought to my attention recently that sometimes codes are stored that do NOT trigger it. I've got a nice little OBD-1, so I'll be checking for codes this weeked.

I do believe I have some sort of fuel delivery issue... nothing major FOR NOW, but something I'll be going through (pump, injectors, etc). I did notice that one tank with a bottle of STP Fuel Injector Cleaner really helped the drive-ability of the vehicle. I have plans further on up the road to have the fuel injectors cleaned and/or replaced, as money allows.

Everything in your third bit of advice is very GOOD advice. I plan on doing that right after re-testing this weekend.

I did take the space plate off and cleaned it up, as well as ghanged the gasket, and made sure the nuts were properly torqued this time around. All that was left of the spacer gasket was as thin as tissue paper... I was awfully surprised when I saw what the NEW gasket looked like!


03-13-2008, 06:17 PM
And it wouldn't kill me to get off my butt and check those spark plugs already, either.

03-15-2008, 08:42 PM
The good news: Since playing with the EGR, I really am idling a whole lot better.

The bad news: Failed AGAIN for high NOx today. Even WORSE emissions than last time.

I think I should start a new thread for the NOx problem since we're so far off topic now.

Thanks again for all the help with the engine stalling/erratic idling problem though!