Oil in coolant...but from where?

[Deathacus]

Hey there! problem is in the title. Yeah. Okay, here's the real scoop. I drained my coolant recently and, well, pretty gunky. What was green didn't look to bad but definatly some kinda oil mix. Where it's comming from? I don't know. I was loosing some coolant but I don't know if it's being burnt or was leaking out a loose hose. I got all the hoses fixed (I accident caused a bigger leak when messing with the throttle) and in that time I've retired her as my daily so she ain't getting a lot of miles. She also has a tendency of intermittent overheating, mostly during idle and low speed driving. Fan and everything works so I don't think it's an airflow issue. Oilwise, I'm losing ~3 quarts between changes, but it looks pretty healthy, no major signs of coolant contamination. I also did a combustion leak test through the rad, it passed, and a cylinder leak test, all cylinders had ~3% leak, and I could only hear a slight hiss through the dipstick tube. There did seem to be an oily buildup on the front valve cover, it's possible that it was from the undercoating (that was last fall and I'm still getting goo running up the hood) So now what? Where do I look?
Engine is a stock 3.0 MTX with 122k

 

[zoomlater]

Are sure it is oil? When I bought one of my cars, I was pretty sure I checked and the coolant was clean. But after not driving it for years (except starting it up once in awhile), I noticed my coolant looked brownish, like oil. I know I had a slight radiator leak so maybe the previous owner tried to add some stop leak in it. It looked sort of like rust in the radiator. I flushed it many many many times until the water came out relatively clear. I then added coolant and have not had the issue since.

 

[Deathacus]

Was yours evenly brown? Mine had the distinct chocolate milkshake look, and it and the green stuff didn't really mix either, like oil and water

 

[Devin]

You are going through 3 qts of oil per change? That seems excessive. And if you were getting that much oil in your coolant I doubt your coolant level would be low.

 

[Deathacus]

Pretty sure halfway down the rad is low

 

[luigisho]

How long have you had this vehicle? anything burning out the exhaust? Is there a sign of coolant leaking? Everything screams head gasket unless there is a radiator leak with a ton of garbage added to it like zoomlater said. Even then Maybe. The overheating can be a bunch of things like HG fail, not enough coolant, clogged passages and whatever oil in the cooling system does to heat transfer. I'd be looking at chipping away at both cooling system and head gasket if there is significant oil in there, This needs to be repaired and flushed all the way through. You can always try a competent professional for a second opinion.

 

[Deathacus]

That makes sense to me but could it be a bad head gasket even with good compression and leak down? Doesn't seem to blow much out the pipe, perhaps just a little fog when it's cold but it doesn't smell like coolant.

 

[luigisho]

Yeah, I get it that it's not following the easier diagnostics. I would also be frustrated and that's why I said maybe pay a pro who hopefully you know is good at this stuff to confirm. I just can't think of any other place where oil can get into the coolant (minus a crack or if there is an oil/liquid cooler that has a failure). Unless it's something else that is oil-like that was put in there. I know coolant can break down into acids over time and lose cooling ability, rust and scaling can occur and discolor coolant but I don't know about consistency and properties of oil in coolant other than oil or other concoctions being introduced into the system. I'm just looking at how possibly and what is the most common answer. No way to be sure from far away.
Send a PM to rubydist and see what he thinks. He's dealt with alot more cars than me.

 

[Deathacus]

I see. Well before I tear anything apart I think I'll borrow a rad test kit just to rule out external leaks. If I do have to get the heads worked on, is there anything else I should look at while I'm in there?

 

[zoomlater]

Was yours evenly brown? Mine had the distinct chocolate milkshake look, and it and the green stuff didn't really mix either, like oil and water

It looked like small brown stuff in the coolant, not completely throughout, not like a milkshake. It was in the overflow bottle as well.

 

[luigisho]

I suppose you could always do a massive cooling system flush, including heater core, get all fresh stuff in there and see what happens over a short period of time.

The overheating is still concerning though

 

[zoomlater]

On a different SHO I had, I would burn a quart of oil every 1000 miles, so 3 quarts every 3000 miles was about where I was at as well. My exhaust tips always had soot. I wonder if the coolant was contaminated enough it wasn't doing its job. Was the thermostat changed recently. Maybe try flushing all the stuff out and refill once its clear.

 

[rubydist]

If it "occasionally overheats" there could easily be a head gasket leak that could allow oil into the coolant. Since the oil pressure is way higher than the coolant pressure, it would likely only go in that direction. You could try doing leakdown testing, but it may not leak all the time given what you said.

 

[luigisho]

I see. Well before I tear anything apart I think I'll borrow a rad test kit just to rule out external leaks. If I do have to get the heads worked on, is there anything else I should look at while I'm in there?

If the heads are coming off, how old or long since timing belt change? That's going to come off anyway and you will have to expose the crankshaft to get a timing belt back on there so front main seal if it is old or leaking. Old upper seals and gaskets obviously. With all that stuff out of the way anything you think is old or was in need of maintenance will be so much easier to access. The heads take up a ton of space. Check and see that the mating surfaces are not warped. Cam seals with the heads out. You still need to flush the crap out of the coolong system. Sucks chasing this stuff but that's the game

 

[Deathacus]

If it "occasionally overheats" there could easily be a head gasket leak that could allow oil into the coolant. Since the oil pressure is way higher than the coolant pressure, it would likely only go in that direction. You could try doing leakdown testing, but it may not leak all the time given what you said.

Okay, I see the theory. I could roll with that. As for timing and whatnot, I already bought a kit for that and something seems to have chewed up the old timing belt a bit so def gonna be replacing those.

 

[luigisho]

Look for anything rubbing in case that needs to be addressed before getting a new one on there. Timing covers are brittle plastic and go on in a particular sequence that might not be the most obvious by looking at it the first time. Good luck with this and post back with updates.

 

[teehud313]

Hey there! problem is in the title. Yeah. Okay, here's the real scoop. I drained my coolant recently and, well, pretty gunky. What was green didn't look to bad but definatly some kinda oil mix. Where it's comming from? I don't know. I was loosing some coolant but I don't know if it's being burnt or was leaking out a loose hose. I got all the hoses fixed (I accident caused a bigger leak when messing with the throttle) and in that time I've retired her as my daily so she ain't getting a lot of miles. She also has a tendency of intermittent overheating, mostly during idle and low speed driving. Fan and everything works so I don't think it's an airflow issue. Oilwise, I'm losing ~3 quarts between changes, but it looks pretty healthy, no major signs of coolant contamination. I also did a combustion leak test through the rad, it passed, and a cylinder leak test, all cylinders had ~3% leak, and I could only hear a slight hiss through the dipstick tube. There did seem to be an oily buildup on the front valve cover, it's possible that it was from the undercoating (that was last fall and I'm still getting goo running up the hood) So now what? Where do I look?
Engine is a stock 3.0 MTX with 122k

I had that issue but it was too late when it was discovered. The problem was the coolant pump, which is located INSIDE the crank case over top the oil pump. Its turned by the timing chain. Mines was loose and had enough play in it to leak antifreeze. That antifreeze falls directly into the oil pan which then pumps through your engine. Your oil and coolant will be flush with "milkshake" as the techs call it. Mines was so bad that flushing it out and making the repairs was far gone. They had to replace the motor, oil pan, and a few other things.

 

[Greg Corcoran]

I had that issue but it was too late when it was discovered. The problem was the coolant pump, which is located INSIDE the crank case over top the oil pump. Its turned by the timing chain. Mines was loose and had enough play in it to leak antifreeze. That antifreeze falls directly into the oil pan which then pumps through your engine. Your oil and coolant will be flush with "milkshake" as the techs call it. Mines was so bad that flushing it out and making the repairs was far gone. They had to replace the motor, oil pan, and a few other things.

Chain? What chain? Anti freeze drops from the WP/chain into oil pan? I suspect we're not talking about an SHO motor here, but an old school push rod motor?? Or there's some design feature of the motor I've never seen in 20 years of SHO ownership including a bad water pump or two...

 

[Fordnut]

Hey there! problem is in the title. Yeah. Okay, here's the real scoop. I drained my coolant recently and, well, pretty gunky. What was green didn't look to bad but definatly some kinda oil mix. Where it's comming from? I don't know. I was loosing some coolant but I don't know if it's being burnt or was leaking out a loose hose. I got all the hoses fixed (I accident caused a bigger leak when messing with the throttle) and in that time I've retired her as my daily so she ain't getting a lot of miles. She also has a tendency of intermittent overheating, mostly during idle and low speed driving. Fan and everything works so I don't think it's an airflow issue. Oilwise, I'm losing ~3 quarts between changes, but it looks pretty healthy, no major signs of coolant contamination. I also did a combustion leak test through the rad, it passed, and a cylinder leak test, all cylinders had ~3% leak, and I could only hear a slight hiss through the dipstick tube. There did seem to be an oily buildup on the front valve cover, it's possible that it was from the undercoating (that was last fall and I'm still getting goo running up the hood) So now what? Where do I look?
Engine is a stock 3.0 MTX with 122k

Well id probably guess you could have a slight blow by from the heads. Or just an aging coolant system. I would start with a full flush of the coolant including heater core. There is probably deterioration and clogging within which would give you the overheating during idle. If youre loosing 3 qts of oil between oil changes is a bit of a cause of concern. If its not external then most likely heads and the sparkplug gaskets. My 1st gen does leak a bit into the plugs (on the overhaul list when i pull the motor)

 

[Deathacus]

I had that issue but it was too late when it was discovered. The problem was the coolant pump, which is located INSIDE the crank case over top the oil pump. Its turned by the timing chain. Mines was loose and had enough play in it to leak antifreeze. That antifreeze falls directly into the oil pan which then pumps through your engine. Your oil and coolant will be flush with "milkshake" as the techs call it. Mines was so bad that flushing it out and making the repairs was far gone. They had to replace the motor, oil pan, and a few other things.

Yeah, you have a different motor there. Mine has a dry belt for the timing, as far as I know no oil goes anywhere near the pump.

As for the oil leaks I forgot that I still had a leaking cam seal so that's a thing