Engine Oil Leaks

David Morris · Post by **David Morris** » Sun Apr 12, 2009 4:57 pm

Hi everyone,

Much has been said about the tendency of our Javelin/Jupiter engines to develop nasty oil leaks and I know from bitter personal experience over the past 40 years what a pain this can be.

Even last year, John Airey and I were changing the rear timing case gasket on our Javelin, DCB 246 [ aka Black Shadow ] in the Hotel car park at Crieff, after she had left a series of oil spots from Bath to Crieff to reach the Rally!

Anyway, sterner methods were obviously required and John Airey, Chris Cole and I have been looking at the excellent work done earlier by Leo Bolter and Philip Dingle et al, using an aluminium gasket and nitrile 'O' rings as a gasket beneath the flange of the rear timing case. John has tried this on his Javelin for several months now and it works, so it was now my turn to try this solution.

John had been very helpful and had made me an aluminium gasket for the Series 3 [ 5/8" banjos ] rear timing cover on Black Shadow, which then uses three identical 'O' rings to seal-in the oil. Two of the three 'O' ring holes needed to be oval. I have just finished fitting it and have returned from a 15 mile proving run. The engine top channels are DRY!! Wonderful! Many thanks John.

We had to look at three examples of the Series 3 [ 5/8" banjos ] rear timing covers and corresponding blocks to assess the best 'fit' around the oil holes from all three and John managed to arrive at what looks like it might be a 'one-size-fits-all' gasket. However, in passing, we noticed that there is what looks like a common failing on all three, which may be yet another oil leakage point. I should mention that all three rear timing covers were marked J54547 and carried a casting ident 'GBF'.

This concerns the tapping on the nearside of the rear timing cover for the oil pressure gauge take-off point. On earlier [ 1/2" banjo ] versions of the rear cover there is a fair amount of 'meat' around this tapped hole, at least 5mm all round. However, on these later Series 3 [ 5/8" banjos ] versions there is just 2mm 'land' on the bottom lip, if that. Two of the castings we looked at had a horizontal crack in the side wall of the tapped oil pressure take-off hole and the third, which I have just fitted, had been welded-up in this area. The tapping had then been reduced to 5/16" BSF, which then entailed John kindly reducing the brass adaptor and cutting a suitable thread on it.

It looks as though the aluminium casting is too thin in this area and I guess many others may be similarly cracked and may be leaking oil here. As the crack is at the bottom of the oil pressure take-off point, it is out of sight and may lead the owner to believe the flange gasket is leaking [again!], which may not be the case. From the top of the engine, it would be very difficult to see where the oil was coming from, being either the flange gasket or a suspect crack in the oil pressure take-off.

If [ or rather when ] you have the later 5/8" banjos rear timing case off again and in your hand, it might be worth looking carefully at the cast boss for the oil pressure take-off and checking for any hair-line cracks in this area.

All the best and very many thanks for all the help and advice that I have received.

David

Post by **Forumadmin** » Sun Apr 12, 2009 8:09 pm

Very interesting, will look at my stock and check the one that is on the JAv that leaks slightly.

Drummond Black · Post by **Drummond Black** » Mon Apr 13, 2009 8:40 am

David, Following your post I went out and checked all the 5/8 Dia banjo holed rear timing castings that I could lay my hands on. I found seven and the outcome was as follows.

Four had a large land at the lower side of the oil pressure gauge tapped hole and were OK.

Three had the reduced land with very little material at the lower side and of these TWO were cracked.

We learn about these cars every day. THANKS David Well done.

Drummond

David Morris · Post by **David Morris** » Mon Apr 13, 2009 11:21 am

Hi Drummond,

Many thanks for your reply.

Most interesting! It looks, from what you have found, as if there are at least two types of rear timing case covers, all with the 5/8" banjos.

By the way, were these ones with the large land all marked with the J54547 number and did they carry the 'GBF' casting ident?

Sorry that you found two of the ones with the narrow lands were cracked, but it bears out the view that the castings were weak in this area.

All the best,

David

Drummond Black · Post by **Drummond Black** » Mon Apr 13, 2009 11:57 am

David, The mistery deepens.

The rear castings with the LARGE land all have NO casting numbers or marks. The casting shape in that area ( where you normally find the casting number is much thicker and ends up at the same level as the rim.

I will try and take a picture later and put it on the forum.

Drummond

Drummond Black · Post by **Drummond Black** » Mon Apr 13, 2009 9:37 pm

Just found a casting with part no 53030 GBF This No is on the Timing Case side just below the top banjo boss. It has a 5/8" dia banjo thread.

Drummond

David Morris · Post by **David Morris** » Fri Apr 17, 2009 10:49 am

Hi Drummond,

Many thanks for your updates.

It look as though you have found two versions of interim rear covers, that bridge the Series 2 versions and the later Series 3 types. Jowett's must have been experimenting again!

Yours have the 5/8" banjo fittings, but from the photos you sent me your 53030 cover looks as though it has the 5/16" feed from the oil pump, rather than the later Series 3 covers, which should have the larger 7/16" oilway drillings for the feed from the pump.

You mention that you have found four castings with no numbers on them. I wonder if these have the larger oil delivery holes? If so, then these are well worth holding on to, as they will be good spares.

All the best,

David

Drummond Black · Post by **Drummond Black** » Fri Apr 17, 2009 8:18 pm

David, Don't worry. I throw very little Jowett bits away.
Drummond

TedAllen · Post by **TedAllen** » Fri Apr 17, 2009 10:18 pm

One item I am running short of is the rear timing cover. I do , however, have an early one in very good order, without the banjos, which I do not need as I do not use a cooler.

Does anyone know if the rest of the stuff is available...filter bowl, seal, bolt and filter ?

Ted

Post by **Forumadmin** » Sat Apr 18, 2009 6:59 pm

Can we see the photos on JowettTalk or JowettGallery please?

David Morris · Post by **David Morris** » Mon Apr 20, 2009 7:43 am

Hi,

I am very ashamed to admit that uploading pictures to either JowettTalk or JowettGallery is beyond my abilities at present.

I have looked at the 'hints and tips' sections of JowettTalk and there does not seem to be a tutorial on how to do this that I can understand.

I have tried using the 'UploadPic' icon on JowettTalk and if this has worked, then there should be three pictures of the later rear timing case. If not, then you can see that I am having problems and not doing something that I should?

All the best,

David

Drummond Black · Post by **Drummond Black** » Mon Apr 20, 2009 8:07 am

David, Keith, I also tried to upload pics of our findings. Although I have done this successfully before I struggled this time. Good to know that I am not alone. We should the Jowett Juniors to educate us.

Post by **Forumadmin** » Wed Apr 22, 2009 9:00 am

Click uploadPic
Browse to picture you want
Click open.
click send
Wait for picture to come up in window.
Click standard

Hey ho.

Please let me know if this does not work and perhaps phone me.

David Morris · Post by **David Morris** » Wed Apr 22, 2009 11:15 pm

Hi,

Many thanks for the tutorial.

Here goes!

Note that 1074 shows the hairline crack in the oil pressure take-off boss and 1076 shows the narrow land in the pressure take-off casting, adjacent to the hairline crack.

Unfortunately, I cannot see the pictures in the post, so I have probably done something wrong?

Many thanks anyway,

David

David Morris · Post by **David Morris** » Wed Apr 22, 2009 11:17 pm

Hey - it worked!

1074 is the left-hand photo and 1076 is on the right.

Many thanks,

David

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