piston rings/big ends and access

[steveNZ]

Hi all
Despite my best efforts to avoid this its looking like i need new rings on my 1988 Bighorn, the blow bye is just forcing up to much oil
Going to have to do this myself and i am hoping to leave the engine in truck as removing it is a major and i don't have access to a hoist anymore.
Im hoping i can drop the front diff housing off and remove the cross member that runs between the to sides of the chassis this should hopefully give enough room to drop the sump off

Has anyone done this before and is there any major obstacles i need to know about ?
Also any ideas on the best place here in NZ to get the rings and big end shells at the best price ?

i am hoping because its chrome cylinder linings i should be able to just replace rings and big ends

Have i been given the right info that chrome liners don't ware so much and that rings alone will do?
Also i understand the 4jb1t has metal head gasket?

Thanks

Steve

[Paulo]

Hi Steve,
For parts try http://www.isuzupartsspecialist.co.nz/ they also have a trademe page they seem to have lots of parts for bighorns also on good price delivered to you. Good luck with everything.

[wbski007]

I have no idea what you mean by big ends, does it mean rod and crank bearings?? cause if you do rings you should do them also.

[turnturn]

"Big Ends" means the bearings at the big end of the connecting rod (conrod to crank).
It's a common term in New Zealand and Australia (England too, by the looks of it, if steveNZ is using it).

[steveNZ]

Yes always in the UK referd to as big end shells not even sure what else you would call them
Have got some good prices now rings for $79 bearings for $80 and head gasket for $100 so not to bad

[steveNZ]

Rings from Johnson piston rings nz http://www.hotfrog.co.nz/Companies/Johnson-Piston-Rings
Gasket and bearings from super cheap auto

[haven]

got some good prices for rings,both bearings and head gasket from sprint autos, ttal round 300 bucks.... though i spoke to a guy on ebay who sells engine rebuild kits and he's trying to tell me you cant juts replace rings without replacing and machining sleeves in bore and pistons... can anyone confirm or deny this from someone who's done this or rebuilds these motors??? dont wanna go ahead and get parts just yet if this is the case....

[steveNZ]

As far as im aware if you have got chrome plated liners which are standard on these engines they cant be machined or honed and providing there not to worn out you can just replace the rings, if they are to worn out you need to replace the hole liner with new ones
If it was steel liners then you would have to replace or get them honed
As for the pistons there are steps in the manual that tell you how to inspect them to see if there ok

[steveNZ]

got some good prices for rings,both bearings and head gasket from sprint autos, ttal round 300 bucks.... though i spoke to a guy on ebay who sells engine rebuild kits and he's trying to tell me you cant juts replace rings without replacing and machining sleeves in bore and pistons... can anyone confirm or deny this from someone who's done this or rebuilds these motors??? dont wanna go ahead and get parts just yet if this is the case....

Has a good chat with a engine rebuild head mechanic today he says that providing you check the sleeve diameters are even so the sleeve is still properly round, he said because it chrome plated sleeves just replacing the rings is fine make sure you have the correct rings
He also said that measuring the piston projetion and getting the right thickness head gasket is vary important dont trust the gasket you take off as its possible that the wrong one has been used before
he said inexperienced people tend to just buy the thickest gasket to be safe doing this will lead to lower compression if a thinner one is required
Also regarding bedding the rings in they need to work in short bursts under load as soon as possable
Find a deserted rd 4 th gear at 3000rpm plus foot to the floor then brake bringing the speed down to about 60 km still with excelarator pushed hard in then when at 60km release the break do this a few times during running in as it help get the engine under proper load in shot bursts

[steveNZ]

Did a compression test today all 4 cylinders are around 350psi (bottom limit 310psi and top limit 440psi) so not to bad for a old engine.
After chatting with the rebuild mechanic today about my engine i am going to hold back on doing the rings for a bit, he seemed to think that because of the compression reading and the fact that my oil rings are fine i should wait and try loading my engine a bit as described in the above post, he also thought the ball bearing valve in catch can was likely to have contributed to the excess oil

My engine has been to pieces before you can see the gasket goo between sump and block
He thinks there's a high chance the head gasket is thicker than the one needed saying that it was often seen on engines they rebuild, This would explain the compression being nearer to the bottom limmit
This intern could affect the ability of the top ring to bed properly as it beveled back into piston so the turbo pressure helps push the ring out.
Checking the head gasket and replacing with correct gasket thickness would up the compression and help push the top rings out and reduce blow bye.

Might take the head off next couple of weeks check piston projection and correct the gasket thickness
much easier than doing the rings at this point and will be interesting to see if he is correct

[wbski007]

I had that funny feeling it wasn't your rings at fault, Steve

[haven]

"As for the pistons there are steps in the manual that tell you how to inspect them to see if there ok"

would love to but i cant get my hands on a manual anywhere!!!
^^^ thanks for all the advice, good food for thought. ill def hold off till i compression test it and or pull it apart to see what the internals are looking like before i look to far into liners,etc..

did any of the machiners tell you what the thickness of the headgasket you should use is? i spoke to sprints and they just told me whats listed under the 4jb1t jackaroo engine but after what you've said im not sure sure i trust sprints knowledge...

wouldnt have thought of that bedding in technique either for the rings, big help there also.might smash out a compression test at work tommorow and see how i go...

[pig75]

would love to but i cant get my hands on a manual anywhere!!!

You can download the namual from here http://daemon4x4.org/portal/downloads.php?dcid=5&p=2 and get the KB-TF140 Workshop Manual. Or i can post you the manual

[haven]

yea man if you could post me that manual that would be ace, cant find the right one for the 4jb1t.....

[geeves]

If you just want the engine manual send me a pm with an email address (it 5meg) If you want the lot pm pig as he can post it to you cheaper than I can