Lister JP3M leak

[flatplane8]

Hi,

 

This weekend I cleaned the JP3M engine in Misterton and ran it for half an hour. Once it was shut down I could hear a hissing noise and on investigation, I could see bubbles coming from the middle cylinder head join with the crankcase. Looking further, it looks like the leak was also evident on the crankcase door here....

 

The engine starts easily enough (by hand) and runs with very little trace of smoke, so I'm thinking that its probably in reasonable condition.

 

I guess as a first attempt at a cure I should check that the cylinder heads are torqued down enough. Failing that, possibly a new head gasket?

 

Does anyone know what the torque figures are for the various bolts? I have a manual, but it just says to 'tighten them up'.

If that doesn't work, is replacing the head gaskets straight forward, and should the existing copper gaskets be reused?

 

Thanks in advance,

 

Simon

[frangar]

Hiya

 

Sorry but your link to the pic doesnt worl so cant quite see what you mean but......

 

You could try retorquing the head nuts.....I used about 120 lb/foot but be careful cos the outside studs can break......dont ask me how I know this......

 

I would use new gaskets which are available from Marine Engine Services at about £30 each

 

If you do take the heads off then check the liners are slightly raised above the level of the block as this lip is used as part of the seal

 

You will need to remove the rocker shaft to get to the nuts at the bottom of the push rod tubes which is a right pain on a JP4 as you will be lucky if you can pull the shafts all the way through the rest of the heads without taking them off

 

Try smearing a bit of Wellseal on the faces when you reassemble.....it can be fun trying to stop the water leaks even if you have stopped any compression leaks

 

If it starts and runs ok without putting "air" into the cooling water then TBH I would just keep an eye on it......Mine "made" air into the closed cooling system so I had to sort it out.

 

Please feel free to PM me if you want any further info....Oh you will need a good selection of Whit spanners and sockets.....and you will learn some new words!

 

Cheers

 

Gareth

[flatplane8]

Hiya

 

Sorry but your link to the pic doesnt worl so cant quite see what you mean but......

 

You could try retorquing the head nuts.....I used about 120 lb/foot but be careful cos the outside studs can break......dont ask me how I know this......

 

I would use new gaskets which are available from Marine Engine Services at about £30 each

 

If you do take the heads off then check the liners are slightly raised above the level of the block as this lip is used as part of the seal

 

You will need to remove the rocker shaft to get to the nuts at the bottom of the push rod tubes which is a right pain on a JP4 as you will be lucky if you can pull the shafts all the way through the rest of the heads without taking them off

 

Try smearing a bit of Wellseal on the faces when you reassemble.....it can be fun trying to stop the water leaks even if you have stopped any compression leaks

 

If it starts and runs ok without putting "air" into the cooling water then TBH I would just keep an eye on it......Mine "made" air into the closed cooling system so I had to sort it out.

 

Please feel free to PM me if you want any further info....Oh you will need a good selection of Whit spanners and sockets.....and you will learn some new words!

 

Cheers

 

Gareth

 

 

Thanks Gareth, some good advice there. On the subject of rocker shafts, I see from the manual you're meant to grease these occasionally, but there are no grease fittings on mine - is this usual?

 

Mine is raw water cooled, so its hard to tell if air is getting in there.

[frangar]

It may be that you have one of the JP variants (JK/JS) which have an oil feed to the rocker shaftd.....do you have oil pipes running to the rocker shafts???....maybe inside the head??

It might also be that the greasers are missing....mine have been replaced with grease nipples...can you see if there is a threaded "hole" on the heads where something should be fitted

 

Also the hissing from the side doors may be casued by a blocked crankcase breather....this should be by the silencer if its s "m" mairine model with the water cooled manifold and dry sump...there should also be a tube from the bottom of the crankcase (on the small side door) to the oil tank.

 

It sounds like you may just have a coolant leak rather than a compression leak....as I said it can be tricky to seal the water passages as they suffer from corrosion....when the engine is running try taking the rocker covers off and see if there are any bubbles coming up through the oil.....if there is then its probably a compression leak....if not its probably coolant which isnt quite so serious unless its leaking into the cylinders as well.

 

Hope this helps

 

Gareth

[zenataomm]

You can view the OP's photo of the crankcase door if you right click the icon and open it in a new tab

[flatplane8]

It may be that you have one of the JP variants (JK/JS) which have an oil feed to the rocker shaftd.....do you have oil pipes running to the rocker shafts???....maybe inside the head??

It might also be that the greasers are missing....mine have been replaced with grease nipples...can you see if there is a threaded "hole" on the heads where something should be fitted

 

Also the hissing from the side doors may be casued by a blocked crankcase breather....this should be by the silencer if its s "m" mairine model with the water cooled manifold and dry sump...there should also be a tube from the bottom of the crankcase (on the small side door) to the oil tank.

 

It sounds like you may just have a coolant leak rather than a compression leak....as I said it can be tricky to seal the water passages as they suffer from corrosion....when the engine is running try taking the rocker covers off and see if there are any bubbles coming up through the oil.....if there is then its probably a compression leak....if not its probably coolant which isnt quite so serious unless its leaking into the cylinders as well.

 

Hope this helps

 

Gareth

 

Thanks again for the reply Gareth. I suspect my greasers are missing, there is no oil feed to the heads that I can see unless its internal (1948 JP3M).

 

The crankcase breather is a good tip, I'll check that its clear.

 

The bubbles/hissing is from the join between the cylinder head and the crankcase. This was evident when the engine had just been shut down, which is kind of strange as with the raw water cooling its not a pressurised system (like a closed circuit one would typically be). Also in the picture (if you can see it) it looked like oil leaking rather than water.

 

Anyway, I've got a few more things to check when I'm next up there.

[Timleech]

Thanks again for the reply Gareth. I suspect my greasers are missing, there is no oil feed to the heads that I can see unless its internal (1948 JP3M).

 

The crankcase breather is a good tip, I'll check that its clear.

 

The bubbles/hissing is from the join between the cylinder head and the crankcase. This was evident when the engine had just been shut down, which is kind of strange as with the raw water cooling its not a pressurised system (like a closed circuit one would typically be). Also in the picture (if you can see it) it looked like oil leaking rather than water.

 

Anyway, I've got a few more things to check when I'm next up there.

 

The later engines with oil fed rockers came only in the 1960s, I think. The pipes are external, readily visible.

 

I'm not seeing any sort of link or icon for the pictures.

 

If it looks like oil leaking, oil can only really come from the well around the pushrods where there is no pressure, it would just be gravity/capillary leak and wouldn't hiss. I'll hazard a guess it might be combustion products, containing oily carbon, from a slight compression leak at the gasket. If that's the case, fix it sooner rather than later. Odd bits of oil or coolant weepage are sometimes just one of the joys of running an old engine provided they aren't causing cross-contamination.

 

Tim

[WotEver]

I'm not seeing any sort of link or icon for the pictures.

 

Me neither.

 

Not that I'd be of any help with the problem, but just to affirm that the image link is broken.

 

T.

[Rojja]

Me neither.

 

Not that I'd be of any help with the problem, but just to affirm that the image link is broken.

 

T.

 

With a bit of fiddling

 

http://misterton.squarespace.com/storage/j.../Listerleak.JPG

 

Mebbe this will work

 

Maybe it won't

 

Roj

[WotEver]

With a bit of fiddling

 

http://misterton.squarespace.com/storage/j.../Listerleak.JPG

 

Mebbe this will work

 

Maybe it won't

 

Roj

 

Well... both of those links work (they take you to http://misterton.squarespace.com/storage/j...Listerleak.JPG) but there ain't not no picture at that location - it results in the following error message: "Page Not Found

The page /storage/june-2009/Listerleak.JPG could not be located on this website.

 

Maybe that's why the original link doesn't work?

 

Cheers,

Tone

[Timleech]

With a bit of fiddling

 

http://misterton.squarespace.com/storage/j.../Listerleak.JPG

 

Mebbe this will work

 

Maybe it won't

 

Roj

 

 

No.

 

Tim

[WotEver]

It's working now

[Rojja]

No.

 

Tim

 

Tim,

From my laptop it works fine, from this box it doesn't so...

I've copied it to here:-

 

Fingers crossed

 

Q) What odds do I give for it working?

A) Equal or less than unity

 

Roj.

[frangar]

After looking at the picture (thanks guys!) it looks like its oil from the side doors......I would check the breathers and maybe make yourself a new gasket - cork is best - its best not to use any sort of joining compound on the door as you should clean the sump out when you do an oil change and this door gives the best access.

 

Have Fun

 

Gareth

 

PS cheers Tim for the info on JK/JS.....wasnt sure when they were introduced and have never seen one in real life!!

[flatplane8]

Hi All, Thanks for the information and sorry about the link not working, it worked for me, but maybe as I have access to the website.

 

I've put a picture at the bottom of the page here

I'll check the breathers, as thats the easiest thing to do, and then work my way through the other options.

 

It sounds like my rocker shafts should have greasers fitted, seeing as the originals are no longer there, can I just use a common or garden grease nipple?

 

Also, is normal lithium grease suitable for this (and the water pump)?

 

Sorry for all the questions.

[frangar]

It sounds like my rocker shafts should have greasers fitted, seeing as the originals are no longer there, can I just use a common or garden grease nipple?

 

Also, is normal lithium grease suitable for this (and the water pump)?

 

Hi

 

Mine just has normal grease nipples fitted...although you might need a right angle one for the back cylinder so that you can get the gun on between the head and silencer....I'm not quite sure how the greaser fits the middle head because I have a JP2 and I'm away from the boat at the mo so cant look at the manual....I'm also not sure of what thread is used for the nipples.

 

Normal Lithium grease is fine for the rockers but I would try to find a water pump grease for the water pump......I have a new Jabsco pump fitted now but when I had an older type of Jabsco I used to use a water pump grease which was white in colour and was supllied my Morris's....I'm not sure if its still made but I have found this:

 

http://www.frost.co.uk/item_Detail.asp?pro...t=Miscellaneous

 

Keep asking btw cos I love my JP...most of the time!!!

 

Cheers

 

Gareth

[flatplane8]

As a bit of an update, I checked the breathers this weekend and they seem fine. I had a look with the engine running and we took a short video clip here You can see the leak quite clearly at the joint. All three cylinder heads have a leak like this of some description. The video is of the pushrod side of the cylinder heads if that helps, the other side doesn't seem to have a leak.

 

Is it worth re-torquing the cylinder heads, or are these leaks likely here to stay? I'm not familiar with copper head gaskets, I know composite ones don't tend to respond to re-torquing.

Edited June 29, 2009 by flatplane8

[Yoda]

As a bit of an update, I checked the breathers this weekend and they seem fine. I had a look with the engine running and we took a short video clip here You can see the leak quite clearly at the joint. All three cylinder heads have a leak like this of some description. The video is of the pushrod side of the cylinder heads if that helps, the other side doesn't seem to have a leak.

 

Is it worth re-torquing the cylinder heads, or are these leaks likely here to stay? I'm not familiar with copper head gaskets, I know composite ones don't tend to respond to re-torquing.

 

No don't re-torque the heads, just leave them until you can do a service.

 

When you remove all of the heads, take the copper gaskets and heat treat them so they are soft. Clean everything and regrind the valves to seal. Re-assemble the heads and torque them up in a diagonal way so they go down flat.

[Timleech]

No don't re-torque the heads, just leave them until you can do a service.

 

When you remove all of the heads, take the copper gaskets and heat treat them so they are soft. Clean everything and regrind the valves to seal. Re-assemble the heads and torque them up in a diagonal way so they go down flat.

 

Original JP head gaskets were copper/asbestos, with possible copper shims to adjust the head clearances.

 

Tim

[flatplane8]

Original JP head gaskets were copper/asbestos, with possible copper shims to adjust the head clearances.

 

Tim

 

 

Ah, for some reason I thought they were copper, the manual seems to imply they are to be re-used, hence my confusion.

 

Thanks!

[Arnot]

Ah, for some reason I thought they were copper, the manual seems to imply they are to be re-used, hence my confusion.

 

Thanks!

I seem to remember that an old trick whan using a copper asbestos gasket more times than was good for it was to paint it with shellac to improve the seal. Maybe what you can see bubbling out is shellac? Either way my feeling is that it's time to lift the heads and invest in gaskets...

 

Regards

 

Arnot

[Chris-B]

I have got some headgaskets if you are interested

 

Chris

[FadeToScarlet]

I have got some headgaskets if you are interested

 

Chris

 

Baldock sidles up in a trench-coat.

 

"pssst! Wanna buy some headgaskets?"

Edited June 30, 2009 by FadeToScarlet

[flatplane8]

I have got some headgaskets if you are interested

 

Chris

 

 

Might well be, do you have three of them? Does your workplace re-condition cylinder heads? I'm now thinking if I'm going to take the heads off, maybe they should get de-coked and checked over by professionals......

[Proper Job]

Hi All, Thanks for the information and sorry about the link not working, it worked for me, but maybe as I have access to the website.

 

I've put a picture at the bottom of the page here

I'll check the breathers, as thats the easiest thing to do, and then work my way through the other options.

 

It sounds like my rocker shafts should have greasers fitted, seeing as the originals are no longer there, can I just use a common or garden grease nipple?

 

Also, is normal lithium grease suitable for this (and the water pump)?

 

Sorry for all the questions.

I have screw cap on my JP3 for rocker greasing. The end cylinders are direct on to the ends of the rocker shaft and the central cylinder has an extension tube with a 90 deg' bend. To fit one on the central cylinder would probably require removing an end cylinder head.

 

I give mine one turn just before starting and the half a turn every few hours running. Every now and then you need to pop the rocker covers off and remove and grease build up that oozes out around the rockers

 

I've put a couple of photo's on my gallery (?) which just about show the greasers