JP3 Thowing Oil out of Exhaust

[BWM]

6 hours ago, alan_fincher said:

The rebuilder didn't happen to have the initials JR, by any chance?

Yep, and from what i've heard since i got off lightly!

[BEngo]

Three or 400 hours is barely enough to have run it in, even if it was worked hard fairly regularly.  I would not be surprised to find the oil  problem is bore glazing.

 

 If you can find any, try Morris"s Ambesta.  If not you would need to re hone the rings and the bores.  An oiled bit of 600 grit wet and dry worked diagonally up and down the bore will do if you can't access a power hone.

Go round the ring outside surfaces  parallel with the top with the wet and dry too.  Then wipe it all  perfectly clean.

 

N

 

[frangar]

7 hours ago, BEngo said:

Three or 400 hours is barely enough to have run it in, even if it was worked hard fairly regularly.  I would not be surprised to find the oil  problem is bore glazing.

 

 If you can find any, try Morris"s Ambesta.  If not you would need to re hone the rings and the bores.  An oiled bit of 600 grit wet and dry worked diagonally up and down the bore will do if you can't access a power hone.

Go round the ring outside surfaces  parallel with the top with the wet and dry too.  Then wipe it all  perfectly clean.

 

N

 

I’m not sure that’s the answer if chrome liners are fitted. 

[john.k]

If the bores are still chrome ,no ordinary honing will mark the chrome ......you need diamond or CBN stones that cost around 200 quid a set of 4.

[Ken X]

Interesting subject this.  Looking to broaden my education so here goes.  We were told when apprentices, that the bore/ring interface generated a seal by mutual wear.  This eventually resulted in excessive bore and ring wear at which point a rebuild was necessary involving reboring the bores, oversize rings etc.  The idea of a chrome bore was to transfer the vast majority of the wear to the rings and reduce rebuild costs and complexity.    When I ran a BMW flat twin bike we were told to just scotchbrite the chrome bores, to remove any glazing, and make very sure to fit the correct rings for a chrome bore.  I believe they were of a material which was soft enough to allow wear against the hard chrome bore and form the required seal.  If a chrome bore became damaged or eventually wore excessively, renewal was required as honing risked damaging the chrome layer.

 

The big, big no-no was to fit chrome rings into a chrome bore.  Running a hard surface against a similar hard surface would cause bad things to happen.  No wear, therefore no seal, low compression, low power and impressive amounts of oil bypass.

 

I cannot remember if there was any particular running-in procedure for new rings in chrome bores as it was many years ago but suspect there was.  As I say, all this was many years ago and I may have misremembered some points so look forward to correction if required.

 

[RLWP]

I'm seeing industrial JP's that have now worn through the chrome in the liners. Leads to lots of oil coming out of the exhaust

 

Richard

[john.k]

Anyway ,I d be identifying which cylinder was the worst for passing oil ,and take off the head to see whats going on...................a word of warning.......a high sump oil level will also cause oil flooding  of the cylinders ,if the crank throws /big ends actually dip in the oil. while running.

[steve.sharratt]

1 hour ago, john.k said:

Anyway ,I d be identifying which cylinder was the worst for passing oil ,and take off the head to see whats going on...................a word of warning.......a high sump oil level will also cause oil flooding  of the cylinders ,if the crank throws /big ends actually dip in the oil. while running.

I oil the rockers every day as was advised but was always concerned that I was essentially adding oil to the engine progressively which could result in overfilling.  I now use a small oil pump can and direct the smallest amount at the moving parts only. I was told that the oil should fill the ‘basin’ at the rockers but I have two Lister manuals and I can only see a reference to that after major works, not daily routine.  I have never worked out what is right.   My current oil level is not over but is at the top mark of the dipstick.  

[Eeyore]

38 minutes ago, steve.sharratt said:

I oil the rockers every day as was advised but was always concerned that I was essentially adding oil to the engine progressively which could result in overfilling.  I now use a small oil pump can and direct the smallest amount at the moving parts only. I was told that the oil should fill the ‘basin’ at the rockers but I have two Lister manuals and I can only see a reference to that after major works, not daily routine.  I have never worked out what is right.   My current oil level is not over but is at the top mark of the dipstick.  

There would be no harm in reducing the oil level to midway between min and max marks on the stick. No real logic here, but it worked well enough on my old BMC which had a particular dislike of being filled to the max mark.

You can often spot which cylinder is passing oil by just looking at the state of the exhaust gaskets. They can appear black and oily even when correctly tightened. If that proves inconclusive you will need to remove the exhaust manifold to see what’s in the exhaust ports.

Have you tried listening to each cylinder using the screwdriver method? You might be able to detect a difference in one cylinder if there’s a broken ring chattering around.

Edited February 22, 2023 by Eeyore

[Eeyore]

Has any JP owner/builder come across instances where the ring gaps have become aligned? Or is that not possible in these engines? 

[tommylad]

On 22/02/2023 at 10:32, steve.sharratt said:

I oil the rockers every day as was advised but was always concerned that I was essentially adding oil to the engine progressively which could result in overfilling.  I now use a small oil pump can and direct the smallest amount at the moving parts only. I was told that the oil should fill the ‘basin’ at the rockers but I have two Lister manuals and I can only see a reference to that after major works, not daily routine.  I have never worked out what is right.   My current oil level is not over but is at the top mark of the dipstick.  

I think this could well be the candidate for the oil in the exhaust. In my experience by the time the oil can overflow down the push rod tubes it's already above the valve guides, so oil can track down the exhaust valve stem and then onwards to your hair/clothes/wine glass etc 😛

If you've already reduced oiling to a minimum it might be worth waiting a while to see if this fixes the problem

[magnetman]

Might it be worth moving an infrared thermometer about on the exhaust manifold in case one cylinder is running wrong. The sound on the brief youtube clip seemed like a missed fire. Someone else mentioned the compression reducing arrangement on these engines. Has it been checked that these are closing properly? Coked up possibly?

[Motorboater]

Not sure if there is much relevance here as I am not mechanically minded, but I seem to remember Richard Milligan vintage engine marine engineer, mention something to do with rebuilt JPs non original head gaskets and having to fill the oil to half way up the nut under the rocker cover so they don't chuck oil out.

 

I may have the above bottom about face, but he looks after my JP2 and many other old engines maybe give him a call.

[steve.sharratt]

4 hours ago, tommylad said:

I think this could well be the candidate for the oil in the exhaust. In my experience by the time the oil can overflow down the push rod tubes it's already above the valve guides, so oil can track down the exhaust valve stem and then onwards to your hair/clothes/wine glass etc 😛

If you've already reduced oiling to a minimum it might be worth waiting a while to see if this fixes the problem

Agreed.

[magnetman]

I did wonder if the dip stick might not be the original one which came with the engine. 

Edited February 23, 2023 by magnetman

[steve.sharratt]

4 hours ago, magnetman said:

Might it be worth moving an infrared thermometer about on the exhaust manifold in case one cylinder is running wrong. The sound on the brief youtube clip seemed like a missed fire. Someone else mentioned the compression reducing arrangement on these engines. Has it been checked that these are closing properly? Coked up possibly?

I do have a IR thermo so will try that.  I do think that the compression dials could be an issue.  One is stuck in (I assume it’s coked up). I played around with them yesterday but need to check the manual to see how they are removed.   It’s worth trying to clean them regardless. 

1 minute ago, magnetman said:

I did wonder if the dip stick might not be the original one which came with the engine. 

That’s a thought.  It’s old but may not be correct.  Another one to check!