OIl leak advice

[Deleted]

I am looking for help on finding an oil leak on my 3 litre, Mk II. The car had its engine rebuilt a couple of years ago but sat for one year before I purchased it. The rebuilder used gasket sealer on most of the gaskets instead of replacing with new gasket.

At first, the engine was leaking at highway speeds at the rate of 1 quart per 80 miles.

The first two leaks were fixed by replacing the top and side valve cover gaskets.

The next leak was found at the rear of the engine at the upper banjo bolt. I replaced the copper washer and tightened the bolt. This fixed the leak. I also tightened the lower banjo bolt and veified that it is not leaking.

Unfortunately, I still have a significant oil leak. It is probably down to 1 quart in 160 miles. I cannot see any oil from the top of the engine. The oil leak appears as multiple from the bottom of the car. The drips are concentrated from center to right hand side of the bottom of the car and from the back of the engine to underneath the right front seat. It seems like the oil is running along the bottom of the car.

I would appreciate any advice on where to look. I am hoping that I can solve the problem without needing to replace the rear oil seal.

There is some oil on the sump and I am thinking that the sump gasket might need to be replaced. However, I am not convinced that the sump gasket could be responsible for the leak.

The key to this leak seems to be the speed of the engine. I can idle the car for hours and not get the same leaking I get on a twenty minute drive on the highway.

Thanks for any advice.

[lagain]

I do not know any thing about the 3 litre engine ! but, could it be leaking from the oil filter, the V8 has a canister but if the 3 litre has a cartridge it can be difficult to get the sealing ring correct. You think it is ok but it's not. Thoroughly clean the block and then trace the oil up. The problem is that the oil will always drip off the sump, making you think that it is the sump gasket.

[Phil Nottingham]

It could well be the sealing ring - I always remove the whole filter body from the block and then unscrew the filter housing. Thing is the oil filter is on the left-hand side of the engine looking from the driving seat - which way is your right side side?

What is on the RHS centr is the oil vent/separator and if oil drops are coming out of this then you have a serious problem like worn bore/piston rings or just perhaps one failed piston/broken rings. The failure to use new gaskets on an engine rebuild does not sound good as its a short cut and lack care. Starting an engine after standing which has rusted bores/rings can also break the rings and score the bores

Check the compressions and look for other signs of crankcase pressurisation like fuming from the two breathers

It could be just the gasket on it the breather though or lack of it again - its worth changing the sump gasket or at least making sure the setscrews are all tight.

PS - Normal oil consumption on these engines can be down to as much 120 mpp - mine went down to 50 mmp and still did not smoke - the fumes from the breather were getting a little heavy though so yours at 75 mmp is getting bad

[Deleted]

Phil,

Thank you for the response. I do not see any significant oil from the breather. My engine has NADA modifications so my beather tube aims up. I have disconnected it from intake manifold vacuum so it vents up towards the front of the engine.

When I first purchased the car I checked the engine compression and got readings between 138 to 142 psi. The readings appeared uniform.

I am disappointed that so many cork gaskets were just coated with silicon sealer and reused. It is so easy to buy cork and remake them.

The oil filter housing might be another place where a gasket was reused. I'll remove the filter housing and examine the gaskets. However, it is really on the opposite side of the engine and there are no drips close to the filter housing.

Is there anything on the rear of the engine, other than the banjo bolts that might leak? It is hard to see with an inspection mirror and I have not been able to find anything in the service manual.

[Phil Nottingham]

I am not aware of anything else on the rear of the engine that you have not already checked except that its very easy to get the top tappet cover gasket slightly out of line.

It could also be the cylinder head gasket or the "O" that is in the rear of head, either missing or was not replaced, for the oil drain. Removal of the head is therefore reuired to check either.

The compressions are a little on the low side but not too bad.

Rear oil seal if leaking will drop oil from the bottom of the bell-housing

[Deleted]

Phil,

It looks liike I have addressed the significant external oil leaks by renewing the valve cover gaskets and tightening up the banjo bolts. I am still getting some dripping but it is no longer significant.

Unfortunately, I still have high oil consumption, one quart in 60-80 miles so the engine must be burning it. On heavy accelerator, I notice a cloud of smoke coming from the exhaust. At first I thought it was black but on second look it seems blue. The cloud is only visible on heavy acceleration at highway speeds.

Can you tell me tell me the probably sources of my oil consumption and how I might test to determine which one is the cause?

By the way, I am not burning any antifreeze and I have the proper 4lb radiator cap.

Thanks.

[Phil Nottingham]

It looks like Sticking/worn piston rings/bores - the O rings in the valve stems do not last long but will not cause that heavy oil burning. If the bores are not too scored/worn oil control ring used to be fitted but this still means removing the head and the sump and usually machining a new wider groove in the piston

[Phil Nottingham]

It also occured to me to try to find out what "reconditioning" has been done to this engine - its a long shot but if its been rebored the rings will take some time to bed in even though it is strange that it burning so much oil under acceleration

[Smallfry]

If the "rebuilder" did not replace the gaskets (the cheap bit) maybe he used some pre enjoyed piston rings as well ?

Other things I have seen over the years, is +10 pistons in +20 bores, re used head gaskets, and piston rings upside down.

Sorry to be cynical (I prefer to call it realistic) but I wouldn't imagine the quality of this rebuild would be up to much, and by what you are saying about the leaks and the oil consumption. I think you will have to pull out the engine again sometime.

[Deleted]

Phil,

It looks like the rings were changed and have about 1000 miles on them. There doesn't appear to have been any work done on the cylinder walls. How long would it take for the rings to bed in?

[Phil Nottingham]

Give it another 1000 miles - one or more could have broken with careless fitting or failure to use stepped ones/or removal of the ridge at the top of the bore. The reasonably lowish compression readings point to poor bedding in.

If the piston rings grooves are worn too wide they give a pumping action with the oil

[Deleted]

Phil,

I got the whole engine sealed up. Most of the leaking oil was due to the crank breather oil seal. I am still using oil at a high rate and wanted some additional advice.

First, if I am accelerating on the highway and then abruptly take my foot off the gas I get enough blue smoke to see in the rearview mirror. This seems to indicate that the valve seals are leaking.

Second, I have examined the crank breather outlet and do not see any hint of oil. The crank breather on my car points upward (NADA) and should be connected to a PCV valve. I have the PCV valve disconnected and the breather open to the air. If it was spitting oil, I would see oil on the intake manifold.

Third, I have driven about 2000 miles since the rings were changed and the compression test shows between 138-142 PSI for all cylinders.

Finally, the oil consumption increases with increasing highway speed. If I drive at 55 mph Ithe engine uses one quart in 80 miles. If I drive 75 mph the engine uses one quart in 40 miles.

I am planning to pull the head and replace the valve guide "o" ring seals. Do you think that the majority of the oil consumption is due to the valve guides or the rings? What level of oil consumption is acceptable?

Thanks

[Phil Nottingham]

I doubt it but given the track record of the reconditioner he may have not changed the O rings. These quicly harden and are difficult to see.

They are near the top of the guide and they usually have to be picked out with a sharpe rt angled scriber.

These engine are havy on oil but mich less than 120 mpp is not normal as are your compressions with supposedly new rings.

I hope it is these seals - how is the power output - it should have quite a bit of "go"