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Alarming amount of oil in the expansion tank

3K views 15 replies 9 participants last post by  Matthew 
#1 ·
My 2.0 NA 9000CSE's expansion tank has a lot of oil in it. Some of it is emulsified, some's just oil! It's a slick on top of the coolant.

Today I did a hydrocarbons test for head gasket failure, but the test passed. No hydrocarbons.

The car does use coolant, and it does use oil.

There is no mayo on the oil dipstick.

The engine feels lumpy at high idle, but picks up fine. Feels like the lumpiness is not a misfire, but transmitted vibration from something else.

There is quite a lot of oil down the front left face of the block (as you look at the enigine bay from the front) beginning at the joint between head and block.

There's a cooling system leak somewhere that I can find, but I can see evidence of coolant spraying out of something. Attempting to work out the coolant spray's trajectory, it appears to be coming from the joint between block and head.

I don't even know if it's possible for coolant or oil to leak from betwen the block and head. Is suppose it is, if the gasket ruptures in the right place.

This problem is getting worse. I have no idea what's going on and I already have my other car in pieces. I don't need any more car grief!

Any ideas?

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#3 ·
Good theory, but if the oil and water ways were now connected via a broken gasket, wouldn't the cooling system's higher pressure force water into the oil? I have never found mayo on the dipstick.

My assumption that the cooling system is at higher pressure is just that; I don't actually know but just strongly suspect.

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#5 ·
Nope, hate the stuff :lol:

Some additional information.

I have noticed what I consider to be an excessive amount of steam from the exhaust. I think this persists even when the engine's warm (I'll have to double check) and is intermittent.

There are also drivability issues. A lack of power, and a distinct feeling that the engine's not happy being revved. I've responded to that by driving the car much gentler than I normally do.

Having said that, the engine picks up fine without hesitation or misfires (see note about lumpy high idle above).

No starting problems.

Car had a coolant flush and change, plus new thermostat last Summer.

The more I think about this, the more I think it can only be a head gasket leak of some strange type.

Still baffled :confused:

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#6 ·
IIRC the oil circuit runs at higher pressure than the water [nominal 2 bar Vs 4 or something like that] so if you have failure across the gasket joint between oil and water ways then oil will weep into the water. It is about the only place this can happen on these cars right? Headgasket or head cracked. :eek:
 
#7 ·
Cracked head could do this as would a gasket failure outside the compression ring. Oil pressure is generally MUCH higher than coolant pressure.


I assume you don't have an automatic gearbox because if you do the transmission oil cooler inside the radiator can give these symptms when it leaks (in early cars, I am unsure whether this is still true of later models).
Pressure test the cooling system, not just cylinder compression. Are you losing oil also?
 
#9 ·
These are all good suggestions.

The car has never overheated, so I don't think the head's cracked.

The car does lose some oil yes. Around half a litre every 800 miles or so. I don't think the oil's being burnt.

The radiator I fitted on the car last year is one for an automatic. Euro Car Parts, despite my argument, insisted that only the one design of rad is made for the car. I ran out of time, and had to take their word for it but now I regret that decision.

However, the ports for the auto trans cooler are blocked off, so there can be no oil leakage there.

I haven't done a cylinder compression test, which is stupid because I thought to do the hydrocarbons test. I won't be able to do the test until next weekend, if the car lasts that long.

As for a cooling system pressure test, well the kit to do that is very expensive and I don't own one. Is there a cheap method? Foot pump?

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#10 · (Edited)
Since I just got through replacing a blow head gasket...I might offer a tip on this.

If you yank a sparkplug and shine a flashlight down into the offending cylinder, it will be clear if there is a coolant leak or not: the piston top will be shiny clean...as will the sparkplug. Coolant does a phenomenal job of cleaning pistons.

For comparison, shine down into non-offending cylinders and you will be greated with black piston tops.

Furthermore, burning coolant gives off the most atrocious stench. While I do not recommend inhaling car exhaust, a quick sniff will confirm the odor
 
#11 ·
Definitely sounds like a head gasket. If it were me, I would take the valve cover off and check the headbolts for tightness. If any are loose, I would get NEW bolts and retorque the head. I had an oil leak to the outside of the motor that I cured using this method.

If it doesn't work, you are out $35 and about 1-2 hours of your time. Worth the gamble in my book.
 
#12 ·
You can have head crack or head gasket failure and it may not affect compression, this test will only tell you the seal between cylinder, head and block is good nothing else; there's an awful lot more seal surface besides those wee rings.

Poor coolant change intervals can rot the copper washer [galvanic corrosion] in the headgasket around the oil pressure up-pipe seal and it can pee out either down the block or into the water.
 
#13 ·
The car made it the 100 miles to Basingstoke this morning. Idle is lumpier particularly at around 1250RPM) but no drivability issues.

I realised today that every car I've owned has blown its head gasket. Except one, but that burnt out an exhaust valve but the repair job was similar.

None of those blown head gaskets ever caused overheating, or water in the oil. Combustion of coolant and oil in the cooling system do seem to be the most common symptoms.

I think I'd better renew my break down cover... pronto :eek:

PetesGriffon said:
If you yank a sparkplug and shine a flashlight down into the offending cylinder, it will be clear if there is a coolant leak or not
I think I've ruled out a leak of coolant into the combustion chamber through the hydrocarbons test.

ragtopcav said:
Poor coolant change intervals can rot the copper washer [galvanic corrosion] in the headgasket around the oil pressure up-pipe seal and it can pee out either down the block or into the water.
The coolant I drained out last year was the colour of dishwater :evil: Couldn't have been changed for years and years :roll:

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#14 · (Edited)
With no time or enthusiasm for repairing anything (already have one car in bits) I decided to pay someone else to do the repair work for me :eek:

The car's now in a garage. They'll diagnose the faults and perform repairs as necessary.

I'll report back here in what they find. I've been warned that that LPG can crack cylinder heads. Not sure how :confused:

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#15 ·
On the "steam from the exhaust" point... if its doing it when the car is well and truly warmed up, one fairly good test is to hold your hand close to the pipe and if your hand gets wet, in say 5-10 seconds, bets are you do have a headgasket prob.
 
#16 · (Edited)
The report back from the garage is a disintegrated head gasket. They said the gasket hadn't so much blown in one place, but was just falling apart. Perhaps with 211,500 miles that's not surprising.

The cylinder head was not cracked and is in very good condition.

They fitted a replacement expansion tank, as the old one was clogged up with oil sludge. Also cleaned out the idle valve, as the idle was a touch variable and the engine would sometimes stall when the car came to a halt.

Also had them fix the gear linkage (knackered bushing), fix and re-gas the air con and replace the tensioner pulley.

All that lot took four days.

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