: 1994 Eldorado sometimes misfiring. Water in the Fuel?



rjpier61
10-16-05, 06:26 PM
Hi people. I'm new here and this is my 1st caddy. I'm happy that there is such a forum & website. I have had it a week & it's nice but I knew there were some issues. One thing I'm looking for advice for is that the engine runs strong mostly, it has just over 81,000 miles, but once in a while it starts misfiring, back firing and spuddering and I have no power until it clears. During this time the engine coolant temp rises quickly. up and unyil it will overheat. I thought it might be water in the fuel tank but I have been treating it with dry gas. I put on about 150 miles but this symptom of misfiring has happened quite abit. Then I thought it might be a head gasket but there is no coolent in the oil, no sweet smell at the exhaust but the coolent will blow out of the overflow relief line at the coolent cap only when the engine is sputtering (over heating or not) . Head gasket? Thanks for any advice. :bouncy:

mcowden
10-16-05, 07:26 PM
Hi people. I'm new here and this is my 1st caddy. I'm happy that there is such a forum & website. I have had it a week & it's nice but I knew there were some issues. One thing I'm looking for advice for is that the engine runs strong mostly, it has just over 81,000 miles, but once in a while it starts misfiring, back firing and spuddering and I have no power until it clears. During this time the engine coolant temp rises quickly. up and unyil it will overheat. I thought it might be water in the fuel tank but I have been treating it with dry gas. I put on about 150 miles but this symptom of misfiring has happened quite abit. Then I thought it might be a head gasket but there is no coolent in the oil, no sweet smell at the exhaust but the coolent will blow out of the overflow relief line at the coolent cap only when the engine is sputtering (over heating or not) . Head gasket? Thanks for any advice. :bouncy:

You should get a cylinder pressurization test done. They (or you) make an air hose fitting from a hollowed out spark plug, turn over the engine to close the valves for the first cylinder you will test, then hook the cylinder up to 120 PSI shop air. If it holds 120 PSI, that cylinder is good, move on to the next. It will take some time, but it's a definitive test. A shop can also test for hydrocarbons in the coolant, which is a pretty good indicator but not always 100% accurate. The symptoms you're describing do sound a lot like a head gasket leak. On the Northstar, you won't see coolant in the oil if the head gasket is blown. If it's just blowing compressed air and exhaust into the cooling system, it will become overpressurized and come out the pressure cap, like you're describing.

Use the Search feature above and look for head gasket. You can also look in the Tech Tips forum (use the Quick Jump drop down box below). There is lots of information about this problem available.

rjpier61
10-16-05, 07:34 PM
Michael,

Thank you very much for the quick responce. :bouncy:

Ron

Ranger
10-16-05, 08:01 PM
When the cylinders are pressurized also look for bubbles in the surge tank (not what you want to see).

rjpier61
10-16-05, 10:41 PM
Ranger,

Thank you too. I suspect it's probibly a head gasket. Hope it is at least on the front head. I'm going to purchase the factory service manuals because I want to do these repairs myself. Ha..... Actually I need to do it myself due to funds.... But your help in diagnosing may help limit unnecessary dissassembly.

Thanks again.

Ron

davesdeville
10-17-05, 04:29 AM
If it is the headgasket, even if it is the front head, it's a better plan to drop the cradle and do all 20 holes. Whatever caused the front one to go is working on the back one as well.

rjpier61
10-17-05, 12:02 PM
davesdeville,

When you're right, you're right. Might as well do it right the 1st time and get it over with.

Thanks,

Ron

rjpier61
10-17-05, 09:40 PM
Ok......... Here is what I feared. I got the title today in the mail. It basically sat on a used car lot since March of 05. When I got it it had about 50 miles more than the last time the title was changed in March. When I picked it up it had just over a 1/4 tank of gas. So it sat for more than 6 months with between 1/2 & 1/4 tank of gas. Can the once in a while misfiring & sputtering be caused by water in the fuel or can the coolent cause this situation on and off. I pretty much figured it has a blown head gasket because the pressure in the coolent system blows before it reaches overheating temps.

Ranger
10-17-05, 10:36 PM
I don't think sitting for that amount of time would cause much problems. If you are in an area that has 10% ethanol, that would dry out any moisture in the tank. If not, add a pint or so of iso-somethingorother alcohol or an over the counter gas dryer to the tank to be sure. That would eliminate that that possible cause.

Oops, rereading your first post, I see you've already covered that base. BTW, Northstars rarely get coolant in the oil through a blown head gasket like a conventional engine, so don't look for that symptom.

rjpier61
10-18-05, 11:08 AM
Ranger, ok thanks. What about possible coolent being sucked into the cylinder. Would it still fire correctly? It does fire fine mostly with plenty of power but just that every once in a while it's like I just sucked in water into the intake. It takes a while to clear the engine then it runs fine for a wile then starts again. :bomb: Guess taking it one step at a time. But man!!!! I don't have a service manual yet but have been poking around online trying to fine a procedure on head gasket replacement with little luck. But what I see from some pictures, this is a design I'm not used to. I have done engine work years ago on 340 ci Mopar, 350 GM, 351 Ford but this overhead cam stuff. From the look of some cutaways it looks like I have to pull the front engine cover to expose the chains & gears. Looks like a mess and hard access. No wonder people do engine swaps. :crying2:

Ron

zonie77
10-18-05, 12:19 PM
The head gasket job isn't that bad. If you've done work on other v8's you should be able to handle it.

There's a thread in tech tips that gives a lot of info. Read it. If you ever timed a v8 cam you can handle timing 4 at once.

It is hard to access "in the car". Drop the cradle and it's much easier. This is the curse of FWD. Not just Caddy but all FWD's are harder to work on. Make it a v8 and it gets REAL hard. It's just a matter of available space.

Your question about intermittent leaking. Yes, that's what sends most people to left field. You do something and it seems to fix it , then it overheats again, do something else and it works awile. Eventually they get real bad.

I try to get people to test for headgaskets right away, not because I think they all blow, but to save them from shotgunning an overheating problem that's really gaskets. Sometimes it is a radiator or purge line...sometimes gaskets. It's just doing good diagnostics and not spending a bunch of money unnecessarily.

Ranger
10-18-05, 12:59 PM
I think the answer to your question is maybe. A small leak would probably not affect the way it runs but a bad breach probably would as coolant is not flamable. Everything in your original post leads me to think it is not a head gasket, except for the overheating. I think you need to do the cylinder pressure test to confirm or rule out a head gasket for sure.

rjpier61
10-18-05, 08:22 PM
Zonie77, Thanks for the words of encouragement. The car runs at normal temps except when it starts misfiring and sputtering. After the episode it drops back to normal.

Ranger, thanks again. I am going to go that route and pressure each cylinder. Should I go the 120 psi to eash cylinder route or 15 psi at the coolent cap method? I pretty much know what to do & what to look for on both methods but the 15psi seams easier but less reliable. I kinda think the individual 120 PSI on each cylinder would better narrow it down...

I'm going to do this this weekend.

Thanks guys!

Ron

rjpier61
10-18-05, 08:28 PM
Zonie77, Thanks for the words of encouragement. The car runs at normal temps except when it starts misfiring and sputtering. After the episode it drops back to normal.

Ranger, thanks again. I am going to go that route and pressure each cylinder. Should I go the 120 psi to eash cylinder route or 15 psi at the coolent cap method? I pretty much know what to do & what to look for on both methods but the 15psi seams easier but less reliable. I kinda think the individual 120 PSI on each cylinder would better narrow it down...

I'm going to do this this weekend.

Thanks guys!

Ron

Eldyfig
10-18-05, 09:33 PM
I see everyone is on the subject of headgasket, this is a big paranoia with North*s. Like Ranger said, I doubt your misfiring is a headgasket problem. First thing to check in any misfiring case is your plugs, then wires and coil packs. I didn't see any mention of this from your post. Have you checked them?

Ranger
10-18-05, 10:39 PM
You are correct in that the cooling system pressure check is certainly much quicker and easier. I'd try that first and leave it pressurized for several hours. See if it holds pressure. If it doesn't, BE SURE to pull the plugs before you crank it as that migh indicate coolant in the cylinder and we do not want a hydrolock, do we. If the pressure does leak down, have someone else crank the engine and watch for a coolant spray out of one of the plug holes. If the cooling system holds pressure, that is not definate as the breach (if there is one) could be small enough that it only leaks under high pressure (compression). I am still not convinced that a head gasket is your problem. The only thing that worries me is the overheating but timing advance can cause overheating as I recall so it may be something else. You may as well rule out your worst fear though.

rjpier61
10-19-05, 11:53 AM
Eldyfig, thank you for your advice. I have not yet done any investigation on the ignition system but I will look into that along with pressure testing. Thanks again.

Ron

Ranger,

I hear that!!!! That is all I need to do is slug liquid and bust up something internal.

What I plan to do is put pressure on the coolent system with the plugs out and lay a paper towel over each plug hole. Give it some time then crank it over. Which ever towel is wet will tell me where my problem is. If nothing shows up, I'll do one cylinder at a time with air at 120 psi looking for bubbles on the coolent tank.

Thanks,

Ron

Anyway guys, It's been a long time since I did this stuff. I used to do a lot of machanical / electrical stuff on cars in my 20's & 30's. I'm finding as I get older, less mobile and limited access to equipment / facilities to do the proper work, I get frustrated easier. I'm not looking forward to doing a lot of knuckle busting. I try to keep in mind something Clint would say "A man has to know his limitations".

Have a great day gentlemen.

Ron

rjpier61
10-19-05, 12:09 PM
QUESTION......

Will the coolent circulate through the heating system with the heat turned on even if the thermostat is shot & in a closed position?

zonie77
10-19-05, 12:47 PM
I believe it will.

rjpier61
10-19-05, 01:59 PM
zonie77,

Hmmmmmmmmmmmm......:hmm: Interesting........

Thanks.

Ron

Ranger
10-19-05, 06:16 PM
Zonie,
Can you explain that. To my thinking, the stat is a blockage in the system when closed. How will it circulate?

zonie77
10-20-05, 01:35 AM
On most cars the stat blocks the radiator. The heater core (at least one hose) comes off the pump. The coolant is circulating in the engine (and heater core) even when the thermostat is closed. It goes to the rad when the stat opens. The flow in the engine does change somewhat when the stat opens.

peteski
10-20-05, 01:36 AM
QUESTION......

Will the coolent circulate through the heating system with the heat turned on even if the thermostat is shot & in a closed position? YES! Heater circuit bypasses thermostat. It gets hot coolant from a hose attached to the water pump and it returns to a hose back to the block (also attached to the expansion tank). And ther is no shutoff valve, so coolant circulates whenever the water pump is spinning. So, coolant always flows through the heater core. Peteski

rjpier61
10-20-05, 09:28 AM
Ranger, Zonie77 & Peteski,

Thank you very much for your responces. This info is helpfull in troubleshooting. It would be funny but good if all my problem was a bad thermostat and an ignition problem.

Thank you!

Ron

Eldyfig
10-26-05, 01:17 PM
OK, what was the problem? Make any progress?