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Peculiar JP oil leak


frangar

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My JP after running like a dream all summer has suddenly decided to weep oil from the lower exhaust manifold stud as per the picture.

 

I’ve taken the stud out and put it back in and tightened everything down which seems to have stopped it but I’m slightly concerned that it might be something bigger starting...it’s definitely engine oil...but maybe a bit more dirty than I’d expect from the oil in the heads.

 

Ive got great compression. Starts easily by hand using this cylinder first. Oil pressure is fine. Exhaust is normal & dry. 

 

The nuts have never had any sort of washer under them. 

 

All the other studs on both this head & the other one are fine & dry. I can’t see any bubbles through the oil for a weeping head gasket or any sign that there’s any external gas/oil/water leaks from the head. 

 

Im quite happy to put it down as one of those things...or use something to seal the stud into the head if that’s the right thing! 

 

Any thoughts from the team? 

 

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7 minutes ago, RLWP said:

What's your exhaust like?

As clean as a lightly loaded JP gets. Certainly no oil drops on the roof that I’ve noticed. Just light blue smoke on Tick over as it’s always been. I might whip an end off the expansion box to see what it’s like in there but nothing suggests it should be anything other than dry... it’s definitely was coming from round the stud..when I removed the stud a small amount of oil flowed out.

 

I must admit that stud wasn’t screwed into the head as much as it might have been...I’ve got it in more now so it matches the other head.

 

I’ve noticed that the oil level seems to settle lower in that head than the front one. Roughly just level the top of the push rod tube nuts. But once there it doesn’t seem to drop lower when running. 

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I'm in the process of putting my JK4 back together and have done a couple of test runs with no manifolds installed. I've had oil leak from an empty lower stud hole on the inlet port. I've put this down to the hole for the stud being drilled a little too deep and breaking into an oil passageway. I've installed the studs with a little bit of heldite to see if that helps, but I don't think its a big deal.

 

PS I'm pretty sure the JP3 currently installed in our boat does the same thing.

Edited by flatplane8
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37 minutes ago, flatplane8 said:

I'm in the process of putting my JK4 back together and have done a couple of test runs with no manifolds installed. I've had oil leak from an empty lower stud hole on the inlet port. I've put this down to the hole for the stud being drilled a little too deep and breaking into an oil passageway. I've installed the studs with a little bit of heldite to see if that helps, but I don't think its a big deal.

 

PS I'm pretty sure the JP3 currently installed in our boat does the same thing.

That’s reassuring! I’ll take it for a bit of a chug when I get the chance and see if I’ve stopped it when everything is hot. 

29 minutes ago, RLWP said:

I have seen this before, it's oil coming from above the head gasket - presumably from leaking down the outside of the pushrod tubes

 

It's annoying, not terminal

 

Richard

I wondered about that but there’s no evidence of the weep from anywhere other than the stud hole...I suspect that as flatplane says the hole for the stud has gone thro to the pushrod tube and when the oil level is at the top of the pushrod tube it’s finding it’s way out somewhere. I’ll try with the oil level a smidge lower and see what occurs. 

 

Ill keep an eye on it and report back if I find anything else...

 

I really wasn’t looking forward to taking the head off! Thanks for the help. 

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4 hours ago, frangar said:

...I suspect that as flatplane says the hole for the stud has gone thro to the pushrod tube and when the oil level is at the top of the pushrod tube it’s finding it’s way out somewhere. I’ll try with the oil level a smidge lower and see what occurs. 

The stud won't have gone through the pushrod tube, it might have broken into the pushrod tube hole in the head.

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6 minutes ago, steamraiser2 said:

JPs often leak around just about all the studs in the head. Bearing in mind that they were drilled and tapped manually it's not unusual. We put sealant on ours as a matter of course.? Nothing to worry about

Phew!!! Just never had it before and I can get a bit paranoid! 

 

Any particular sealant or just something like hylomar or wellseal? I would like to be able to remove the stud using the two nut technique as it makes it easier to get the manifold & expansion box off as one unit should I need to! 

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8 minutes ago, frangar said:

it makes it easier to get the manifold & expansion box off as one unit should I need to! 

You have three Shredded Wheat for breakfast then?

 

I'm only just strong enough to lift the expansion box, having a manifold waving about on the end would be - challenging

 

Richard

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1 minute ago, RLWP said:

You have three Shredded Wheat for breakfast then?

 

I'm only just strong enough to lift the expansion box, having a manifold waving about on the end would be - challenging

 

Richard

I don’t find it too bad...but that might be why my back gives me grief sometimes!

 

It’s a bit of a challenge to get the lot out the side doors mind you!

 

But it means you don’t have to disturb the expansion box/manifold joint which I have found can be problematic to seal nicely. 

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