1950 Javelin engine oil leak

[Robin Fairservice]

I have rebuilt an engine to be a spare, and have just installed it to try it out. I haven't installed the water pump, or put water in yet; just in case it all has to come out again. I turned it over on the starter motor to ensure that I had oil pressure and that nothing leaked out. All OK. I hooked up the ignition, throttle etc.. and then pressed the starter. After a couple of unsuccessful tries, I played with the distributor and then it fired up and ran up to 3500 rpm! I pushed the choke in and it did not slow. As I reached to turn off the ignition I saw the pressure gauge descending from 90 psi, which alarmed me. When I then looked at the engine, oil was pouring from the right rear corner of the sump flange and there was oil on the lower bolt inside the bell housing, but I cannot see any oil on the back of the fly wheel.

Have I blown the rear seal? Will it reseal if I replace the oil and try again? How could I slow the engine down? I had put 10-30 weight oil in for the intial running.

[David Morris]

Dear Robin,

Firstly, my sympathy! It must have been a blow after a lot of hard work.

What I suspect has happened is that the oil release valve has stuck. Pat Lockyer, I think, mentioned a similar problem a few months ago. What seems to happen is, after a period of idleness, the steel ball in the valve mechanism gets rusted into the seating, especially if there was some previous water in the old oil, and just doesn't come off the seat when needed. Hence the high oil pressure. Now, your question as to whether this has done any damage?

It may, but I suspect not. The rear crankcase seal is a tough old lip seal and might leak a bit with excess pressure, but not burst. I just suspect there was loads of oil flying around at 3500 rpm and where you saw the oil was the lower point of the engine, which I believe, was not in the car?

I suggest you drop the sump and have a careful look at the oil release valve. There are several types of oil pump and some folks have devised methods of testing the release valve. Perhaps they will respond? I know that the JCC Southern Section had a display of the various types of oil pumps on the JCC stand at the Bealieu Autojumble this year, which I should have photographed! Perhaps Ian Roxburgh can help ( 01580-880402 ), as he was a leading light on the stand?

The choice of oil sounds OK for running-in, perhaps a little light for normal running. I use a 20W/50 normally, but then we don't have your winters!

How to slow it down? I can only suggest that you may have a stuck butterfly(s) in the carbs? I suggest having a careful check on the choke mechanism and the throttle rod, to see if the butterflies are properly closed when the engine is at rest.

Finally, a word of encouragement! If you had oil pouring out of the rear timing cover, then you would have burst the gasket, which is a big relief! For that seal to stand up to 90psi or higher is a record - well done!

I hope all goes well,

All the best,

David

[Keith Clements]

90 psi cold is OK. 75psi hot is what the relief should be set at. If there is no oil on flywheel I do not think rear crank seal has gone. Oil on that bolt is unusual. Maybe the case is cracked in that area. Could try putting sealer under the washer.

[TedAllen]

Hi Robin,
I posted earlier on a similar problem I had except my pressure went so high that the filter canister imploded and there was oil everywhere. A change of oil pump cured the problem.
It wasn't clear from your post but was the oiled up bolt in the same corner as the sump flange leak ?
Jowett was very clever in using the bell housing to carry the back of the sump so that any oil that gets past the rear main actually drops back into the sump rather than getting all over the back of the flywheel and then onto the clutch..
One thing I would do before you remove the sump is to check the joint in the leaking corner with a feeler gauge.
It may just be a bad flange or gasket problem.
My engine always starts at around 100 psi when cold and then settles back to about 50 when hot...with 20/50 oil

Good luck
Ted

[Robin Fairservice]

The replies provide for more thought. The oil pump was rebuilt by Neil Moore in NZ so I would have thought that it shouldn't have a rusted relief valve. I saw the display at Daresbury and took photos of the Mk 1 and Mk 2 Oil Pumps. Mine was a Mk 1, but was modified by Neil to be more like a Mk 2. I think that first I will take the bell housing off the engine that came out to try and understand what might have happened, but I will also drop the sump off the "new" engine and re-install with more sealant around it, particularly in the corner where the oil gushed out.
Unfortunately there was so much oil on the floor that I didn''t go under while it was still coming out.

Regarding the engine speed, I have an electric pump with a separate pressure regulator. I think, now, that the regulator got turned up whilst removing and re-installing it. I have a gauge so I will reset the pressure before trying to start it again.

I am going away for a few days, so won't start anything until later next week.

[Mike Allfrey]

Dear Robin,

The late George Gilmore, a very colourful member of the Oz club used to say; "A good Javelin squirts its oil thirty feet!"

I don't have any particular qualms with the 90 psi at start up in the northern hemisphere. However, it should come down to between 60 and 75 psi.

Neil did a few pumps for me and they have all worked well. He did supply one pump a few years ago, with a new manufacture pressure relief valve spring, which on my test rig, tended to straighten out the pipe to the pressure gauge. I had to modify the spring to achieve a reasonable pressure. I was extremely thankful that I had the pump on my test rig at that time!

As for the leak - I am fairly certain that the oil feed passes the upper tie bolt (crankcase) and high pressure oil can escape there. I tend to assemble engines with new flat washers on all bolts and studs that secure the crankcase halves. This probably goes against the grain with respect to the average Jowett owner and/or mechanic - they expect extended life from mutilated plain washers. I also apply a small bead of Loctite 518 Mastergasket under the plain washers and on the crankcase, where the washers seat.

DO NOT apply Loctite 515 or 518 to the three main bearing webs at their joint faces. Doing so will upset the bearing clearances. It will reduce oil pressure somewhat!

With respect to the carburettors, make sure that the cold idle setting link is correctly adjusted. It should only open the throttle butterflies a small amount when the choke cable is fully pulled.

Back to the oil leak, it could be due to a cracked crankcase - that is really sobering though.

Personally, I would not run a freshly overhauled engine without coolant. Heat build up is very quick, and you would see nothing on the temperature gauge.

Best of luck,

Mike Allfrey.