Jump to content

JP2 heads won't lift


Andy_B
 Share

Featured Posts

Suggestions please,  this is a Lister JP2.  I'm trying to get the heads off for a decoke and to trace a low compression problem on one of the pots.

 

All the manifolds are off and the six nuts are off the six big studs on each pot.  I've cranked it through compression a couple of times, to no avail, levered gently between the (two) heads, even bopped it on the side with the mooring mallet via a lump of wood.  Nothing. 

 

Tapping a screwdriver in the edge of the gasket reveals traces of silicon rubber - could some pillock have glued the gaskets down?  

 

Asssuming that's what's up, what suggestions do you have for getting getting the head off?   Be creative.

 

Cheers

 

Andy

 

Link to comment
Share on other sites

You’ve got the nuts off the pushrod tubes I take it?? 
 

Someone had used instant gasket on mine when I first got it...but turning it over on the starter freed it off. I also take it you have the compression changeover screwed right in tight? 

Edited by frangar
Pushed send too early! Again....
  • Greenie 1
  • Horror 1
Link to comment
Share on other sites

You need to take the rocker shaft out & rockers then you can access the nuts that fit on the tubes that the push rods go through. It’s a bit of a fiddle and if it’s a marine JP you will need to remove the silencer as well. 

1 minute ago, Mike the Boilerman said:

 

Well if compression alone won't pop the heads up, try actually starting it.

 

 

I think he’s missed the pushrod tube nuts...there are 8 nuts in total holding a JP head on. 

  • Horror 1
Link to comment
Share on other sites

Pushrod tube nuts . . . ah.  ?

Scurries for the manual to see where those are hidden. . .

 

Well done Frangar.  I certainly need those off before going any further.

 

Thanks for getting straight to it!

 

Do I get a numpty certificate?

  • Haha 1
Link to comment
Share on other sites

4 minutes ago, Andy_B said:

Pushrod tube nuts . . . ah.  ?

Scurries for the manual to see where those are hidden. . .

 

Well done Frangar.  I certainly need those off before going any further.

 

Thanks for getting straight to it!

 

Do I get a numpty certificate?

Suck the oil out and you will see them! They are whitworth but I can’t remember the size off the top of my head. My Britool standard 1/2 drive socket is deep enough over the tubes. Be warned when you do lift them the are bloody heavy and will leak various fluids. I suggest getting a light skim on the heads...I also use wellseal on all the gaskets...including the head/shims if fitted. Pay attention to any corrosion around the waterways...and make sure the liner is slightly raised! 

Link to comment
Share on other sites

20 hours ago, frangar said:

You need to take the rocker shaft out & rockers then you can access the nuts that fit on the tubes that the push rods go through. It’s a bit of a fiddle and if it’s a marine JP you will need to remove the silencer as well. 

Managed to get both rocker shafts out without disturbing the silencer - unscrewed the greaser elbow and pulled it forward.  Gentle application of mole grips. 

Front piston is pitted at the crown, it's not just carbon build up, it's into the metal.  I take it this isn't right?!  Any suggestions other than new piston?

IMG_20191018_134348.jpg

Link to comment
Share on other sites

20 hours ago, frangar said:

. ... I can’t remember the size off the top of my head.

1 5/16" AF. did the job.  I found a 3/4 drive single hex socket in an old tool box, c/w breaker bar.  Perfick

Edited by Andy_B
  • Greenie 1
Link to comment
Share on other sites

38 minutes ago, Andy_B said:

Managed to get both rocker shafts out without disturbing the silencer - unscrewed the greaser elbow and pulled it forward.  Gentle application of mole grips. 

Front piston is pitted at the crown, it's not just carbon build up, it's into the metal.  I take it this isn't right?!  Any suggestions other than new piston?

IMG_20191018_134348.jpg

Well done!! That looks like it’s been letting  water in. Can you see a pattern on the head gasket from where the water has been tracking. It looks from the pic that the liner might be a bit low on one side...I hope I’m wrong!! 

Link to comment
Share on other sites

Might be just the way I've wiped it, the way the liner looks.  I wondered if it'd been left a while somewhere in between being a fishing boat and being a narrow boat and perhaps got water in this pot.  The other one is fine, just light carbon buildup. I've not cleaned it yet but the matching head looks pretty rough too.

Link to comment
Share on other sites

30 minutes ago, Andy_B said:

Might be just the way I've wiped it, the way the liner looks.  I wondered if it'd been left a while somewhere in between being a fishing boat and being a narrow boat and perhaps got water in this pot.  The other one is fine, just light carbon buildup. I've not cleaned it yet but the matching head looks pretty rough too.

Just check there is a even lip all round the liner. Mine was low and it caused all manner of grief until I had it pulled & shimmed. I’d say that looks more than damage from standing water but it might be from old salt water corrosion if it’s out of a fishing boat and the cooking water was leaking into the cylinder in the past. Think you are looking at a new piston & head skim...what state are the liners in? 

Link to comment
Share on other sites

14 hours ago, frangar said:

Just check there is a even lip all round the liner. Mine was low and it caused all manner of grief until I had it pulled & shimmed. I’d say that looks more than damage from standing water but it might be from old salt water corrosion if it’s out of a fishing boat and the cooking water was leaking into the cylinder in the past. Think you are looking at a new piston & head skim...what state are the liners in? 

Likewise, i had one fitted too low which allowed a free exchange of water and fuel oil between cylinder and water jacket. If extreme it will also affect the seals near the base of the liner. 

  What is the sealing face on the cylinder head like?

I'd second the use of wellseal when reassembling. 

Link to comment
Share on other sites

I'm finding these comments very useful, will check the liner and block surface later.  Meanwhile here are some snaps of the heads.  Can anyone see why compression was a bit low on the front pot?

(Rear pot first, front next)

 

15714842369103862562425940924388.jpg

1571484389199183805830888055885.jpg

Link to comment
Share on other sites

On 19/10/2019 at 12:39, Andy_B said:

I've got two tins of carborundum paste. . . ?

Seriously I wonder whether there's enough left for a recut. ?

Ooohh that’s not great. There was a head or two on eBay a few weeks ago. You could also try Marine Power Services on the south coast who’s on here as @martyn 1 or @steamraiser2  I think a new piston is needed too...which means if you’ve pulled the piston you may as well fit a liner...then you notice the big end has some play....then you may as well get the crank ground.....??....I’ve a feeling of dejavu now...? Hopefully you won’t need to go that far!  
 

I’m not sure if you could have an insert put in for the valve either?? 

Link to comment
Share on other sites

On 19/10/2019 at 12:39, Andy_B said:

I've got two tins of carborundum paste. . . ?

Seriously I wonder whether there's enough left for a recut. ?

I doubt you could skim the head to remove the pitting as it looks too deep, needs a replacement. 

 There was a head on eBay for about £350 but i didn't like the look of it, had the appearance of a home 'restoration'.

2 minutes ago, RLWP said:

We have had seat inserts fitted to JP heads. I'm fussy about valve regression 

 

We have pistons, valves, head gaskets,  manuals etc. 

 

Richard 

That head needs more than an insert!

Link to comment
Share on other sites

1 minute ago, BWM said:

I doubt you could skim the head to remove the pitting as it looks too deep, needs a replacement. 

 There was a head on eBay for about £350 but i didn't like the look of it, had the appearance of a home 'restoration'.

I’ve had a look and I can’t see any on there now. There was a “new” crated one on there but it was daft money. 

Link to comment
Share on other sites

Just now, frangar said:

I’ve had a look and I can’t see any on there now. There was a “new” crated one on there but it was daft money. 

There is someone doing ex Mod stock for just shy of £600, boxed and unused. Like you say, mad price but no competition. I'm not sure if that is for a bare head without valves, etc. 

Link to comment
Share on other sites

10 minutes ago, BWM said:

There is someone doing ex Mod stock for just shy of £600, boxed and unused. Like you say, mad price but no competition. I'm not sure if that is for a bare head without valves, etc. 

yeah, saw that - image looks like it has valves but as you say it's silly money!

The other head is better but not perfect and seems to have been welded. 

Oh dear!

 

20 minutes ago, BWM said:
21 minutes ago, RLWP said:

We have had seat inserts fitted to JP heads. I'm fussy about valve regression 

 

We have pistons, valves, head gaskets,  manuals etc. 

 

Richard 

That head needs more than an insert!

Richard - who's done inserts for you - I am inclined to agree with BWM that it's a bit far gone but I'd like a machine shop to look at it first!

 

Link to comment
Share on other sites

Well from the pictures I would be putting that piston and associated head in the scrap bin.

 

Don't forget when you get it sorted and put the heads back on to check the piston to head clearance. All of the indian made head gaskets I have seen to date are to thick and wont allow the clearance to be set correctly. It will run but wont be as clean as it can be. Hence we don't buy the Indian gaskets, we make our own to the OEM thickness.

 

We have used heads as well hear

 

 

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.