TL;DR Oil mixing with the coolant. To fix or not? Will it give me engine issues?


When I first got this car, I had to have some work done on it to get it drivable. Apparently the gear would overheat, and I had it "sorted out". Because of language barrier/issues, I never knew exactly what was replaced, but needless to say that when I checked the coolant level I found some oily residue and the mechanic said it wasn't an issue. This was back in January, and the car's been absolutely fine since. You know, until recently.

About a month back, where I live (GCC country) we transitioned into summer. 40C+ temps. Not a time to be stranded at noon on the side of the road. So, I had a warning light that informed me of low coolant come on for a few minutes and disappear afterwards. Since I was running some errands, I did what any reasonable person would do and took it to the nearest mechanic to get it checked out.

Well, I had plenty of fluid,and by fluid I mean water and probably little to no antifreeze from what I can tell. The guy claimed there was oil in the mixture and it needed addressed ASAP. That particular day I had a ton of stuff to get finished and there was no way I could leave the car there (plus, this particular place overcharges by a lot). I figured if the car isn't really overheating, there's no problem.

A few days ago I was out doing more errands. As I'm almost home the light comes on again, I put some gas and it goes away. I drive the rest of the way home and the car stalls as I'm pulling in. I open the hood, and there's no coolant, as well as the (gasket?) closest to the intake seems to have bubbles of oil coming out of it. Adding some water and turning the car on, I can see exactly where the coolant is leaking from in a small jet.

Mechanic says it's not worth fixing, costs of about $1000 and even then no guarantee that I won't have engine issues. I've had 2 different cars where this same thing happened before, and each time I was able to get it fixed and had zero issues with the engine. I would prefer to keep driving this car for a bit longer as I'm saving up for a car made during the latter half of this decade.

Anyone with info on how bad it could be? Hopefully it's just the big hose that needs replaced ($150) plus labor. Also there may be a hard to reach part that needs replaced under the engine. I'm willing eat up to $500 in costs. Nothing else in the car needs work, and the A/C was running fine when I had the "overheat" so it hopefully didn't get hot enough to damage the engine (drove it about 5 minutes/2 miles with the warning light on.

p.s. If anyone can direct me of what to focus on, I can take pictures later today.

 

I'd pressure test the cooling system to find all the leaks. If the engine is leaking... might want to call that car done. If the leaks are only in the radiator or hoses... then might be worth fixing.

 

Doubtful you have any engine damage due to overheating. The 3.0L has some built-in protections and won't melt itself like the 4.0/4.2.
That's not to say that you don't have engine damage, as oil and coolant ought not be mixed. Just doubtful whatever the problem is that it's due to overheating, more likely a cause thereof.

 

On the last overheat....when you found the no coolant situation, did you immediately add water to the hot engine...if so, did you hear any crackling like water droplets on a hot pan...or even small hisses

 

Sorry I haven't checked the forum in a while, been a bit busy. I did immediately add water, but I don't remember any noises honestly.

The 2nd mechanic I took the car to said something like there's a part that isn't necessary, a cooler (cooling?) part for the oil (engine oil or tranny oil not sure). He said that it's a part he takes off of Porsches and some other cars with no issues. Now, we live in a desert, and temps can get up to 55C (not to mention extra high temps from the sun). Any idea what this part could be and if it's necessary?

As of right now I'm getting this part, and replacing the main "octopus hose" that's connected to where I put water in. No water mixed with the engine oil, and hopefully no other hoses are/were damaged. The car was supposed to be done today, but the guy didn't do anything so I gotta wait till tomorrow. I did request that he use used parts when necessary to keep the costs down, and I'm hoping he sticks to the original quote of $300 to $450 or thereabouts. Much better than the "at least $1200" the original guy claimed.

 

What can I do to prevent this sort of thing from happening. I've had 3 different cars where this exact issue has occurred: a '97 Ford Expedition, an '06 BMW x5 3.0 and now my Jag. It's almost always (as far as I know) caused by the mechanics not filling up antifreeze after doing repair work. I've written this in past posts and gotten a ton of hate, but I'll write it again: where I live the mechanics are 99% out to fleece ya in worse ways than most other parts of the world. I can get into more detail but it's a socio-political thing and I'm not trying to get anyone mad, so I won't.

 

Just check it yourself, it's foolproof.

 

You mean check the coolant level? That's the problem, I not only checked but topped up my coolant (with water, but probably not affect whatever coolant/water mix was there previously)
It was basically full.

Two days later, and I had my situation.

The big questions is, why didn't my A/C stop working/blow hot air? With my previous cars, that's the sign that usually gets me to get the f off the road as I'm not usually eyeing the temp gauge (I do now, almost to OCD levels). On the Jag? Na, A/C was good but I did turn it off once I saw the low coolant warning come on, just in case!

 

DO NOT rely on the instrument cluster temperature gauge to determine if the engine is overheating! The gauge doesn't change between about 96 C and 128 C, which is not going to help you if you're in an area that reaches 55 C in summer.

Use a Bluetooth interface through the OBD port and the Torque app on a smart phone to monitor the coolant temperature.

It's possible the gearbox cooling section of the radiator side tank has failed causing gearbox fluid to mix with the coolant. Once the cooling system is checked for leaks, the gearbox fluid level should also be checked as the ZF 6HP26/28 becomes very unhappy with low fluid levels.

 

Thanks for the advice. Car is all good now except I need to change the spark plugs...either its a new issue or the guy switched some parts as the engine was smooth before I handed over the car.

However the low coolant warning still comes on! I only drove about 12 miles on it. Going back to the guy tomorrow for a gas cap, its been missing for about w weeks if that can affect anything.