Coolant / oil in my spark plug cylinders....

Posted by: M635dude

Coolant / oil in my spark plug cylinders.... - 10/29/11 11:54 AM

Hey guys,

So I've been having some problems lately with my '97 P71 D.A.R.E. car. Started to get the car ready for winter here last week. Replaced the starter, new battery, oil change, fuel filter, and a cat back exhaust system. For the first day the car was running fine, but then on the second night all of a sudden it started missing when I would give it past 1/4 throttle. I thought well since it's been sitting for 5 months maybe there was some dirt settled in the fuel system, water, ect. Gave it a full fuel treatment and continued to drive it. This seemed to have absolutely no affect on the issue. Then cleaned the maf and throttle body, with still no results.

So yesterday I decided I would pull the plugs and try cleaning them up as well as the wires. I go and pull out the spark plug wire tube only to hear it full of a liquid. I put my socket down to the spark plug and sure enough the spark plug cylinder is full of about 3-4 inches of coolant and burnt smelling oil. Is this a head gasket?

After just putting almost $1k into this thing, and then finding out the sills are starting to rot really badly, and now it looks like my headgasket is going, it's been a tough week. Any advice would be greatly appreciated gentlemen. I know there are some extremely knowledgeable people on this forum when it comes to these cars.


* Car misses real bad when throttle applied.
* P0171 - p0174 codes present
* Car is fine when cold, gets progressively worse the warmer it gets.
* Fuel system cleaned out, new filter.
* Coolant / Oil in spark plug chambers
* Maf / throttle body cleaned

Again I would appreciate any input guys, I'm going to be tearing into it today after work to see if I can see where this coolant is coming from. And what would a thread be without pics smile Thanks - Adam West

My dads baby

Posted by: Chrono

Re: Coolant / oil in my spark plug cylinders.... - 10/29/11 12:19 PM

I would be heavily scrutinizing the intake to see if there isn't a crack near the thermostat housing or a crack near the brass nipple on the back that the heater hose connects to. These are the two common failure points on the plastic intakes and when they start to leak they'll fill up a spark plug tube and short out the ignition coils in the process.

As for the oil getting into the spark plug tube, I'd examine the valve cover gaskets and see if it looks like oil has been seeping from around the gasket near the spark plug tubes. When I had to change out the intake on my '99 I ended up having to change the valve cover gaskets as well since some of the plug tubes had oil in them.

Hope this helps and let us know what you find.
Posted by: D-Fenz

Re: Coolant / oil in my spark plug cylinders.... - 10/29/11 12:34 PM

Yeah, coolant in the plugs is normally tell-tale for a cracked intake.
Posted by: M635dude

Re: Coolant / oil in my spark plug cylinders.... - 10/29/11 09:51 PM

Thanks for the input guys.

Took a blow gun and 3/8's rubber hose and blowed out all of the coolant and crap that had filled the spark plugs. The car is running great now and doesn't skip a beat laugh

Cleaned up the intake and I've been looking for a leak, but can't trace it yet. Look like its coming from right above the 2nd furthest back spark plug on the passengers side. The drivers side bank is 100% dry. I will keep an eye out for where the leak is coming from, but it looks like I'm going to need a new intake. Wonder if my aftermarket warranty will cover this job?

Also the coolant crossover/ intake or w/e is the plastic version, not the aluminum one.
Posted by: M635dude

Re: Coolant / oil in my spark plug cylinders.... - 10/29/11 09:54 PM

Just checked my warranty, and the intake manifold is covered! After this job the warranty will have paid itself off and I still have 2 years 2 months left smile
Posted by: Chrono

Re: Coolant / oil in my spark plug cylinders.... - 10/29/11 10:43 PM

If it was #3 and #4 that had coolant in them I'd be willing to bet the coolant nipple on the back of the intake that the hose from the heater core connects to has a crack in it somewhere. That's where mine started leaking from and it filled #3 and #4 with coolant.

Good thing that the intake manifold will be covered. You could see if valve cover gaskets would be covered, too. biggrin