Water in my oil!?

[Ariadne]

Just found I have some very thick grey sludgy oil in my engine (Volvo Penta MD21B) so What I need to know is where is the water coming from? I changed the oil only 20 hours (although dirty black as normal it was water free) or so ago and replaced the head gasket and had the head skimmed last June so its only done about 200 hours.

I've had the oil cooler off and that seems to be OK, I would assume that as the oil is under pressure it would leek to the water, not the other way around? I don't think there is a way for the sea water to leek into the engine via the salt water pump, in any case the water drains out through purpose built holes when the seals go. So can I now assume it is the head gasket that has gone?

Any thoughts from the engineers out there?

 

[Monique]

When you reinstalled the head after planing, did you also use new head bolts? Were they torqued to the recommend value?

My first thought... head gasket leak... but best of luck.

 

[Ariadne]

Cleaned up and re-used the originals, I take it this was the wrong thing to do then?

I can see the logic as they would have already been torqued up and 'stretched', therefor the the torque would need to be higher than before. Is this correct?

So when I fit the new gasket, I should also cost in new head bolts as well?

out of interest, would over tightening cause a gasket to fail or would it just warp the head.

 

[seasolutions]

some engines use stretch bolts some do not, some bolts can be used twice, some three times, some once, some go on for ever...

When you put the head back on you presumably tightened bolts progressively, in pairs, from the centre out? idealy you should re-torque them after about 5 hours running.

also, a crak in the oil cooler could well suck water in as the oils cools after shut down.

 

[Kurrawong_Kid]

Just found I have some very thick grey sludgy oil in my engine (Volvo Penta MD21B) so What I need to know is where is the water coming from? I changed the oil only 20 hours (although dirty black as normal it was water free) or so ago and replaced the head gasket and had the head skimmed last June so its only done about 200 hours.

I've had the oil cooler off and that seems to be OK, I would assume that as the oil is under pressure it would leek to the water, not the other way around? I don't think there is a way for the sea water to leek into the engine via the salt water pump, in any case the water drains out through purpose built holes when the seals go. So can I now assume it is the head gasket that has gone?

Any thoughts from the engineers out there?

I speak from expensive experience! Before you spend any time on the cylinder head etc., take off the waterpump and replace the seals on the shaft. In theory if the outer seal leaks there should be dripping from the hole between the seals, but if the hole is blocked or rusted up and both seals fail, the pump forces water into the sump. I had an engineer change the cylinder head gaskets because I thought that was the problem but it reoccurred and I then discovered the pump problem. There used to be something on the Westerley Owners Group website about this problem.

 

[andy01842]

The important thing to do when you plan the head is to run a tap down the bolt holes in the block as the bolts will now have to go further into the block as the head is thiner. You could be torquing the bolts down on dirt in the bottom of the holes and not on the head!

 

[Ariadne]

Not worried about the water pump - mine leaks like a sieve through the drain holes when an oil seal goes and there ain't any water leaking from there!! I also changed them in March (when I did a complete rebuilt on the pump), even by my standards they shouldn't have gone by now after that rebuild!

Judging by the mayonnaise like stuff around the oil filler cap and the sludge around and in thew oil, I'll go with the head gasket gone.

 

[Jcorstorphine]

water pump

I speak from expensive experience! Before you spend any time on the cylinder head etc., take off the waterpump and replace the seals on the shaft. In theory if the outer seal leaks there should be dripping from the hole between the seals, but if the hole is blocked or rusted up and both seals fail, the pump forces water into the sump. I had an engineer change the cylinder head gaskets because I thought that was the problem but it reoccurred and I then discovered the pump problem. There used to be something on the Westerley Owners Group website about this problem.

Don't dismiss the water pump. Even if it is not showing signs of leaking, it may me that the drain is blocked or the two seals are too close and water is being pumped straight into the sump. I had this on an MD2B. Turned out the previous owner had incorrectly rebuilt the pump with the seals back to back with no gap !!!!!!!!.

 

[Monique]

" Quote" Cleaned up and re-used the originals, I take it this was the wrong thing to do then? " Unquote"

Yep... it may have been a mistake. I have had many high power engines in cars (racing) boats (racing) and all head work started by sourcing new head bolts, studying the maintenance manual to find the correct order and torque figures.

Did I mention a top notch torque gauge??? I hope it turns out OK for you.

Start by removing head, gasket etc. Ensure both block and engine are spotlessly clean. Get a new gasket and install with new bolts including the correct torque figures.

Should not be too expensive IMO. GL

 

[Heckler]

Cleaned up and re-used the originals, I take it this was the wrong thing to do then?

I can see the logic as they would have already been torqued up and 'stretched', therefor the the torque would need to be higher than before. Is this correct?

So when I fit the new gasket, I should also cost in new head bolts as well?

out of interest, would over tightening cause a gasket to fail or would it just warp the head.

Yours is an old peugeot diesel, they didnt need the head bolts renewing like they do nowadays. Put some of the gunge on your tongue, see if its salty. Is the oil in the sump milky or is it just in the rocker box?
Stu

 

[vyv_cox]

Yours is an old peugeot diesel, they didnt need the head bolts renewing like they do nowadays. Put some of the gunge on your tongue, see if its salty. Is the oil in the sump milky or is it just in the rocker box?
Stu

Practical voice of experience! Stu's question is the same as mine when I read the thread. Where is the grey oil? If the whole sump is grey then you are looking for a water leak. But mayonnaise in the rocker cover may well be something else, usually nowadays due to cold running, so maybe thermostat? or just light use?

Using the same bolts on this engine is perfectly acceptable, very different from a racing engine. But recheck the torques before starting to strip it down.

Leakage via the water pump is engine dependent and I don't know yours well enough to comment. This is a persistent problem on Bukhs, where inner seal leakage puts seawater into the sump, even though the drilled hole between the seals may seem to be dumping it to the bilge.

 

[Heckler]

Practical voice of experience! Stu's question is the same as mine when I read the thread. Where is the grey oil? If the whole sump is grey then you are looking for a water leak. But mayonnaise in the rocker cover may well be something else, usually nowadays due to cold running, so maybe thermostat? or just light use?

Using the same bolts on this engine is perfectly acceptable, very different from a racing engine. But recheck the torques before starting to strip it down.

Leakage via the water pump is engine dependent and I don't know yours well enough to comment. This is a persistent problem on Bukhs, where inner seal leakage puts seawater into the sump, even though the drilled hole between the seals may seem to be dumping it to the bilge.

Vyv
If I recall this was the engine used in the quatre cent quatre, the arab donkey as it was called when I was in Algeria!
Again from memory, alloy head, didnt last long if it overheated.
Stu

 

[Ariadne]

The oil in the sump is thick and grey, and there was about a litre extra!! The oil residue in the rocker box is also very thick and grey - like fine mud. The inside of the rocker cover also has white gungy stuff on it as well.

Head off but no sign of it blown or exhaust gas escaping from 1 side to the other. Anyway I need to lift the engine out to drain and clean the sump properly; so I'll give it good seeing too when its ashore on some blocks. Lucky old me, I am on the hard in Alcudia for anti-fouling and to replace the seals in the sail-drive.

Great job in 35C, when I should be swimming and boating instead!!!!!

 

[Pincoya]

I have seen this, twice, this year on other boats. Each time it was the oil cooler heat exchanger that had failed with holes in the tubes. Your assumption that oil pressure is greater than the water pressure is something that I believe is incorrect and you might want to look at the cooler.

Paul

 

[Heckler]

The oil in the sump is thick and grey, and there was about a litre extra!! The oil residue in the rocker box is also very thick and grey - like fine mud. The inside of the rocker cover also has white gungy stuff on it as well.

Head off but no sign of it blown or exhaust gas escaping from 1 side to the other. Anyway I need to lift the engine out to drain and clean the sump properly; so I'll give it good seeing too when its ashore on some blocks. Lucky old me, I am on the hard in Alcudia for anti-fouling and to replace the seals in the sail-drive.

Great job in 35C, when I should be swimming and boating instead!!!!!

OK
water in oil for sure, is it salt or fresh? I was serious, taste it! Just a spot on your finger will tell you.
Suspect this here though, http://www.marinepartseurope.com/en/volvo-penta-explodedview-7742100-26-13882C.aspx Easy enough to bypass it, although oil will eventually come out of the water connections. Easy enough to take the ends off and inspect the tubes one by one, solder both ends of the tube if you find a damaged one.
Stu

 

[SAMYL]

When the head is off check the block surface around the bolt holes to see if there is a raised lip of metal that has been pulled up and that could prevent the head seating properly. You will need a metal rule on its edge or other straight edge laid over the hole to check the 'flatness'. This can also be diagnosed if you rub the block surface gently with a flat metal block and some fine emery, you can then identify the high spots.
Sometimes it is prudent to slightly countersink the bolt holes to remove this lip and prevent it happening again. It may not look like much but it can cause a lot of problems particularly in older engines.

 

[Ariadne]

Great stuff, I'm working my through the system bit by bit - oil cooler seems a god area to check out again, as is the raw water pump set up. It'll be out by dinner tomorrow and checked over - new head gasket as well!!

Will keep you all informed.

Dave

 

[macnorton]

Great stuff, I'm working my through the system bit by bit - oil cooler seems a god area to check out again, as is the raw water pump set up. It'll be out by dinner tomorrow and checked over - new head gasket as well!!

Will keep you all informed.

Dave

I think the 2.1 Peugeot is a wet lined engine, so if its not the cooler or head it could be a liner seal.

Start the engine and bring it up to temp with the header tank cap off, if you get lots of air/fumes out of the header tank hole before getting to normal temp you have your answer?

If the coolant is still clean without fumes/bubbles the engine is fine, It's the cooler or sea water pump.

 

[macnorton]

I would assume that as the oil is under pressure it would leek to the water, not the other way around?

The oil is under more pressure when the engine is running, when you stop the engine the oil is 0 PSI but the engine coolant could be 12 PSI?