New owners preparing to take a JP3M to sea - help!

[Timleech]

Any other ideas?

Yes, take of the expansion box. It's only held with two nuts

 

 

(plus exhaust and water outlet flanges)

 

Tim

[by'eck]

Judging by the way mine came apart and was re-assembled, the silencer body comes off first and goes back on last, after the exhaust manifold is re-fitted.

 

The stud instead of setscrew issue shouldn't make this any more difficult since as Tim mentions, once the two nuts at top of silencer are removed plus exhaust and external water pipe of course, it lifts vertically off the long studs which run through the centre of it into the back of the crankcase.

Edited September 25, 2013 by by'eck

[wren]

Giant will be back in a little bit with the news and photos of the rest of the engine.

 

I'm on cleaning detail tomorrow, armed with rags, a variety of brushes (nylon, brass, steel), a big red tin of GUNK, and WD-40.

 

Any specific recommendations for cleaning, particularly the big studs still attached to the engine block and the vast amounts of red stuff we think is hardened haldite? It's red, it's solid, and it's all over the gaskets and block...

 

My cleaning background is lab chemistry where we clean things with an ultrasonic bath and a variety of controlled solvents, all unavailable outside specialized laboratories.

[George94]

But they do and that is why in the UK we are in the lucky position that the RNLI exists to save people in some cases from there own stupidity.

 

You wouldn't head off for a long drive knowing you brakes are a bit dodgy and one wheel is hanging off. But with boats I have spent many an hour towing in people that are only in danger because of poor preparation and maintenance. You won't believe how many people jump on a boat that hasn't moved for years and head straight to sea without any more checks than does it start.

 

 

Yes, you are right of course. I was being slightly tongue in cheek. But there is always more that could be done, however well prepared you think you are.

[Giant]

OK, so the remaining heads are now off and everything is looking very much the same under those two, including similar additions of extra copper around the waterways on the changeover valve side. Here are the gaskets in place on the second and third cylinders (extra bits of shim are underneath on the right hand side):

 

 

 

From the discolouration in the centre right it looks to me like the gaskets are simply blowing between these extra bits of shim, which seems hardly surprising. Of course the real question is why were they thought needed in the first place.

 

Here is the block with everything off:

 

 

One stud came out along with its nut on the third cylinder. Here's a closeup of the stud exactly as removed:

 

 

This one is from a blind hole and doesn't look like it will be any trouble to reinsert. It is also very much typical of the appearance of what we can see of the others. None of them really give the impression that they have been immersed in water coming up around their lower threads.

 

Our solution to the exhaust situation, incidentally, was to remove studs B, C and E with a non-destructive stud extractor picked up this evening at Halfords.

 

The mystery around stud A deepens, however. One would expect the manifold to now drop freely, but it remains firmly attached to the silencer flange at stud A. The manifold can be pivoted around A, but when doing so the stud does not rotate relative to the silencer. It seems the stud is threaded through both the silencer and the manifold, which I don't understand, since there should never have been a thread on the the silencer side and the thread on the stud is the same size as that of the adjacent set screw - which passes freely through the flange and only meets a thread when it gets to the manifold.

[by'eck]

 

The mystery around stud A deepens, however. One would expect the manifold to now drop freely, but it remains firmly attached to the silencer flange at stud A. The manifold can be pivoted around A, but when doing so the stud does not rotate relative to the silencer. It seems the stud is threaded through both the silencer and the manifold, which I don't understand, since there should never have been a thread on the the silencer side and the thread on the stud is the same size as that of the adjacent set screw - which passes freely through the flange and only meets a thread when it gets to the manifold.

 

Since you haven't mentioned them and there are four in total, can I assume you have removed the other two bolts that secure manifold to silencer ? I believe they are inserted through clearance holes on the underside of manifold and into tapped holes in base of silencer.

 

You can see the tapped and clearance holes in manifold below. Thread size to check if original is 3/8" BSW.

Edited September 26, 2013 by by'eck

[Timleech]

That joint between manifold and expansion box is often a source of trouble, the thin wall between exhaust and water gets eroded close to the joint face, I've seen a variety of bodges on them and maybe the OP's has been bodged in some odd way that will only be revealed when he gets it apart.

 

 

Edit - re-reading the description, my guess would be that the joint has been assembled with some sort of bodging compound, the thread into the manifold was poor (these also suffer from corrosion) and the compound has held the stud into the expansion box more securely than does the thread into the manifold.

 

Tim

Edited September 26, 2013 by Timleech

[Giant]

 

Since you haven't mentioned them and there are four in total, can I assume you have removed the other two bolts that secure manifold to silencer ? I believe they are inserted through clearance holes on the underside of manifold and into tapped holes in base of silencer.

 

Yes, those are out - the manifold is now only secured to the silencer by stud A. I will check what the actual thread sizes are on everything and report back.

 

From what magical source do you have a CAD model of the manifold, by the way?

 

That joint between manifold and expansion box is often a source of trouble, the thin wall between exhaust and water gets eroded close to the joint face, I've seen a variety of bodges on them and maybe the OP's has been bodged in some odd way that will only be revealed when he gets it apart.

 

Edit - re-reading the description, my guess would be that the joint has been assembled with some sort of bodging compound, the thread into the manifold was poor (these also suffer from corrosion) and the compound has held the stud into the expansion box more securely than does the thread into the manifold.

 

That does seem like what has happened, yes.

 

Since we have got what we wanted off already, I am inclined to just leave this bodge alone for now and hope that we have not disturbed it enough to prevent the flange resealing properly when done up again.

 

I think the only sure way to get the stud out now would be to undo all the silencer connections, lift the silencer and manifold off as a unit, and then unscrew one relative to the other. That would leave the stud sitting in the silencer flange where it could then be more easily removed from the lower side of the flange.

[Timleech]

 

Yes, those are out - the manifold is now only secured to the silencer by stud A. I will check what the actual thread sizes are on everything and report back.

 

From what magical source do you have a CAD model of the manifold, by the way?

 

 

That does seem like what has happened, yes.

 

Since we have got what we wanted off already, I am inclined to just leave this bodge alone for now and hope that we have not disturbed it enough to prevent the flange resealing properly when done up again.

 

I think the only sure way to get the stud out now would be to undo all the silencer connections, lift the silencer and manifold off as a unit, and then unscrew one relative to the other. That would leave the stud sitting in the silencer flange where it could then be more easily removed from the lower side of the flange.

 

Have you tried a little gentle persuasion (tap with a hammer) on the end of the stud?

 

Tim

[by'eck]

 

Yes, those are out - the manifold is now only secured to the silencer by stud A. I will check what the actual thread sizes are on everything and report back.

 

From what magical source do you have a CAD model of the manifold, by the way?

 

 

I borrowed it from the MPS website - hope they don't mind. They do/will be offering new JP2 & 3 pattern marine exhaust manifolds. Both Martyn (martyn 1) and his father Geoff (steamraiser2) have replied on this thread.

[Timleech]

 

Yes, those are out - the manifold is now only secured to the silencer by stud A. I will check what the actual thread sizes are on everything and report back.

 

From what magical source do you have a CAD model of the manifold, by the way?

 

 

That does seem like what has happened, yes.

 

Since we have got what we wanted off already, I am inclined to just leave this bodge alone for now and hope that we have not disturbed it enough to prevent the flange resealing properly when done up again.

 

I think the only sure way to get the stud out now would be to undo all the silencer connections, lift the silencer and manifold off as a unit, and then unscrew one relative to the other. That would leave the stud sitting in the silencer flange where it could then be more easily removed from the lower side of the flange.

 

Unfortunately you haven't 'left this bodge alone', the joint has been disturbed. Knowing that these joints can be troublesome, I personally would want to see the state of the joint and mating faces before reassembly.

 

Tim

[martyn 1]

Ha ha, seem as it's you Richard, no I dont mind

 

Incidentally the JP2 manifold is available, JP3's I havent gotten around to the tooling yet. oh and the silencer/expansion box is available as well.

 

I borrowed it from the MPS website - hope they don't mind. They do/will be offering new JP2 & 3 pattern marine exhaust manifolds. Both Martyn (martyn 1) and his father Geoff (steamraiser2) have replied on this thread.

 

I Would have to strongly agree with Tim here, you have already disturbed this joint so it will have to come fully to bits.

 

If you want the wreck your engine after all your hard work dont do this. the head of water in the silencer is enough to fill the exhaust side of the manifold and get into the engine, I had to rebuild a JP3M not long ago that sprung a leak in this area and resulted in two scrap liners where the water had been seeping into the engine for some time without the owner knowing and finally when it properly began to leak badly the engine was running and ended up with a bent rod.

 

 

Unfortunately you haven't 'left this bodge alone', the joint has been disturbed. Knowing that these joints can be troublesome, I personally would want to see the state of the joint and mating faces before reassembly.

 

Tim

[Giant]

Right then.

 

The cylinder heads went to the workshop today and my suspicions were confirmed - they have warped slightly over time and the ends around the water channels now sit a few thou back from the centre of the face. It's only on cylinders 2-3 and worst on number 3, which is roughly consistent with how much fizz was appearing under each when running. Number 1 checked out flat so I suspect that one was only leaking a little because of the bodged shim arrangement that was applied to all three.

 

We are having the warped two skimmed and the valves & seats checked too on all of them while they're in. Meanwhile the injectors went to Peter Slater yesterday and we will pick it all back up on Monday.

 

Regarding the manifold/silencer joint, we will get it all off as advised.

Edited September 26, 2013 by Giant

[Giant]

The manifold is now off and stud A extracted. It took a crowbar between the silencer and the manifold to get it to start moving, but then the gunk around it in the clearance hole gave way and the rest was easy. Once the manifold was free it was easy to extract the stud from it. The mating surfaces don't look too bad, and we are obtaining a new gasket.

 

Only one of the bolts that were securing it is 3/8". The other two and the stud are smaller 5/16". Either the holes have been helicoiled, or some serious bodging compound has been used in them. Wren is having a look now to try and tell which.

[wren]

To follow up, it looks like the hole for Stud A and the one to the right in previous pictures is a wider (3/8 W) threaded hole at the top, and then closes up to a narrower (5/16 W) threaded hole.

 

Does anyone know (can this be extracted from the CAD model?) the original depth of the hole?

 

We are wondering if we are dealing with an original hole which has been extended at a smaller thread or if there has been a helicoil inserted. (More precise visual identification is not really possible due to massive amounts of hardened bodging compound.)

[martyn 1]

 

Does anyone know (can this be extracted from the CAD model?) the original depth of the hole

If you ask nicely I will dig out the machining drawing & model and tell you. ;0)

 

Will look tomorrow

[wren]

I would really appreciate it since, having taken it all apart, the next job is to put it back together! Without leaks.

 

Going off-manual makes me a little nervous.

[martyn 1]

Right. here is an extract from the machining drawing for the JP3 marine manifold. You will spot its been metricised for ease of getting fittings. so in place of the M10 x 1.5 to a depth of 15mm should be 3/8BSW to a depth of 5/8". And before someone points it out I know 15mm is slightly less that 5/8" it was rounded down to the nearest standard metric depth.

 

Hope this clears things up.

Edited September 28, 2013 by martyn 1

[wren]

Hope this clears things up.

 

I am remiss in thanking you (I can offer only that I have spent the last few days chained to the workbench in the engine room, cleaning mating surfaces...), it has cleared things up completely, thank you very much!

 

We are now slowly getting to the point of reassembly...

[martyn 1]

I am remiss in thanking you (I can offer only that I have spent the last few days chained to the workbench in the engine room, cleaning mating surfaces...), it has cleared things up completely, thank you very much!

 

We are now slowly getting to the point of reassembly...

No Problem, always glad to help

[wren]

Sad morning here in Goole, last night we excavated a hairline crack on the port side of the engine block. (Not, I specify, on the top face, but on the side face.)

 

So she won't be going to sea under her own engine, for sure.

 

We really appreciate all the advice and time and help you've given us on this thread, and are pretty devastated that the sea journey isn't going to happen the way we had hoped.

 

So now, I need advice on people able to repair cast iron and/or tugs for the North Sea...

[jake_crew]

_{That's such a shame, but better to find the weak points now I guess.}

 

_{By'ecks post (51 ?) in this thread show pictures of a heavily cracked block.}

 

_{These are "hot", and link to the repair company, Skinners in Dorset. About as far from Goole as you can get I'm afraid.}

 

http://www.crjskinnerwelding.co.uk/gallery.html

 

_{But the "after" pictures look impressive.}

 

 

edit for clarity

Edited October 2, 2013 by jake_crew

[Timleech]

If the cracking is definitely confined to the side of the block, consider getting an in-situ stitched repair done.

Google for Lockstitch and Metalock, or try metalock on zero247636zerozero84.

 

If it's more extensive, then hot welding might be better, These people are a bit nearer than Dorset, I've never used them but a customer is about to do so. It'll mean a complete strip down of the engine, though.

 

Tim

[flatplane8]

Sorry to hear that, we used Alan Pratt to bring Misterton down to Staines a few years ago.

 

Is repairing the engine or fitting another one over the winter an option? I think Alan Pease in Goole had a JP6 for sale.....(bit big perhaps).

[wren]

I certainly hope repairing it is an option! Because of the extremely peculiar nature of the mooring in London, it would be massively preferable to get to dry dock and on the mooring ASAP.