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Exhaust in radiator?

05-13-2009, 05:08 AM
My 95, 3.8, with 88k has been using some antifreeze lately. When I recently opened the overflow tank and the radiator to check on the levels, there was a strange odor in them. It smelled kind of like exhaust gas and gasoline. The coolant is green, not milky, in the radiator. There is a brown scum coating on the upper part of the over flow tank. Sometimes there seems to be a sweet smell inside the car and under the hood. When using the heat, no smell is detected at all as would typically occur with a leaking heater core. The engine oil is fine, not milky either.

I'm not sure if the two are related, but I've been puzzled over a rough start problem that typically happens when you cold start the car for the first time of the day. It usually is fine for at least the rest of the day if not for the next day too. When first started, you think you have a serious tune up problem, but when you give it the gas or just start driving, it immediately clears up. I wonder if antifreeze is leaking into one of the cylinders causing it to initially run rough. I also checked the tailpipe, and it smelled and looked normal inside, though I should recheck it right when first starting it. At one point, there was noticed a large amount of white smoke coming from the tp not long after starting it, but I just thought it was typical of a first start up, but I didn't see it for myself.

Any suggestions as to determining if the exhaust really is getting into the cooling system? I imagine pulling plugs for green, maybe look at O2s for green, compression testing, which is a real PITA on this engine. I was hoping someone can suggest something cheap and easy (:sarcasm1: I know I'm not asking for much) to diagnose this.

I checked for codes to see if there were any and if they could help with any of this. BTW, the CEL hasn't come on at all. These are OBD I or EEC-IV codes.

116-Engine coolant temp higher or lower than expected
114-Air charge temp higher or lower than expected
(aka the sensors are out of range)

No continuous codes

536-BOO circuit not activated during KOER (aka circuit failure)
521-Power steering pressure switch circuit fault (possibly circuit failure)

Any suggestions on remedying these are welcome if you know what common causes of them to repair.

Thanks in advance!

This auto repair business is getting ahead of me with six needing my attention. That leaves me no more fall back vehicles!?! :headshake :screwy::shakehead:banghead:

05-13-2009, 06:40 AM
The KOER codes you have are likely just due to not performing the brake or PS tests during the KOER process. During the KOER test, the scan tool should prompt you to press the brake, goose the throttle, and turn the steering to lock. If you don't do those, you'll get the KOER codes you listed.

As for checking for early stages of head gasket failure, there is a cool little device on the market that you attach to your radiator or recovery tank, bring the car up to temp, then it indicate if there are traces of exhaust present in the cooling system. I'm not sure how many variants of this system there are, the one I've seen uses a liquid that changes colors. This sounds like exactly what you're looking for ( but you'd also need the detection fluid.


05-13-2009, 08:31 AM
There won't be "green" o the plugs or O2. If you smell exhaust in the overflow its time to pull the heads. Its no secret that these are prone to head gasket failure.

05-14-2009, 01:07 AM
Thanks Rod. I reread the code reader manual with fresh eyes and realized I hadn't done the pedal and steering wheel at the right time, (unfortunately, there is no prompt to do those things, just following the directions correctly as to when to do them) so like you said, that's why those two codes came up. That leaves the other two codes. I'll clear the codes and try again. I'll also test the sensors to see if they are within spec for voltage and resistance.

I looked at that tool you linked to. It's very brief on its use and how it works. It doesn't mention the test fluid you mentioned. How did you know that? You have one of these to know the fluid is needed I guess? Couldn't you just use the fluid without the fancy tool? Right off I didn't see this fluid in that site.

I was hoping to avoid pulling both heads if it came to that if only one is leaking. Or would that be a big mistake? Wouldn't checking plugs and the O2 sensors provide an indication of that? I know a plug will be unusually clean if water is getting to it. I would expect doing a compression test on all of the cylinders would indicate which one or ones are bad.

Any chance Ford will do my heads as part of that head gasket debacle/recall? Unfortunately, I believe that has expired but one can still hope if it means I don't have to do it.

Airjer, any other indications besides the exhaust smell, I can look into to verify that I am getting exhaust into the coolant system? Would there be "smoke" coming out of the system? Is the brown scum in the overflow tank related to this? Would my theory of coolant getting into the cylinder be the cause of the short lived rough idle at start up and then clear soon after?

05-14-2009, 06:48 AM
I actually saw these being demonstrated during MotorWeek this week, the liquid changes from blue to yellow if there is exhaust gas in the coolant. I imagine you don't want to add the fluid into the cooling system because it would take a lot and if there was exhaust there, it would change to the color of the coolant. If there wasn't, it would change your coolant to a nasty color anyway and you'd need to change it out. Plus it might make it so you can't recycle the coolant. Here's a link ( that shows the test liquid.

If the leak was bad enough, it would probably change the color of the spark plug slightly and clean the carbon out of the cylinder, but if it were bad enough to do that, you'd already have an indication that the head gasket is shot. As for checking compression, I'm not sure if the leak is bad enough to make a conclusive determination there either. Since you said earlier that checking compression is not easy on this car, you might try the cylinder balance test through the PCM. For the cylinder balance test, the PCM shuts off fuel or spark to one cylinder at a time and looks for one (or more) cylinder(s) that cause a larger drop in engine speed than the norm. I don't recall though if this was available for all EEC Fords or not. Some scan tools will allow you to enable the CBT through a menu, or you can enable it following completion of the KOER test by goosing the throttle if I recall correctly.


05-14-2009, 08:31 AM
We have the bulb tester at the shop and it does work. The other thing you can do is find a shop with a four gas analyzer and have them sniff the coolant. There should not be any hydrocarbons in the coolant but for the benefit of doubt I like to see more than 100ppm and typically when they are bad you can get reading of a 1000ppm or more. The shop will know what you are talking about if you ask them to sniff the coolant for hydrocarbons.

05-15-2009, 09:59 PM
Couldn't I just get some of the test fluid and add it to a sample of the coolant to see the change? I couldn't find just the fluid on that Napa site, but I'll call around to see if I can get something local.

I can comp test the front bank, but the back is just not practical, but I'll try the front while checking the plugs.

I did see and try the cylinder balance test on a 94 Sable with the 3.8, but I'm not sure if it and my 95 actually support that test. I'll have to retry it to be sure it does. I wasn't sure it worked or I can't remember if it did. My tester has you tap the accelerator 5 times to initiate the test right after getting the codes from the KOER test.

Airjer, how much would you expect the sniff test and the bulb test each to cost at a shop?

The car seems to produce more white smoke than I imagine it should, though when I checked it today it's not as severe. What are the consequences of driving this for any amount of time until I can get to it? Would it be a mistake to redo just the one bad head?

05-16-2009, 09:31 AM
he test fluid is sampling the vapor/steam of the coolant. The fluid will turn from a dark blue to a light green/yellow color. If you add coolant to it it will not work as there is not enough hydrocarbons in the small sample to make a difference.

One other thing is to just run it with the radiator cap off and watch the coolant. If it constantly percolates than thats another sign of a failed head gasket.

The white smoke out the tail pipe is another.

Time to pull the trigger and pull the heads, have a machine shop inspect them and replace the head gaskets! Wait to long and you'll start to get coolant in the oil which is no good.

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