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Old 04-09-2021, 12:05   #16
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Re: replace or repair 4.108 perkins 1989

If the engine was overheated at some point due to some sort of cooling system issue, it is possible for the rings to lose their tension and then have a loss in compression. Thus if one disassembles the engine and finds almost no measurable wear, one may only have to re-hone the cylinders and re-ring the pistons and after the break in period for the new rings be back to original performance. Of course at the same time it makes sense to replace any seals, since they deteriorate with time alone. Thus new valve stem seals, front and rear crank seals and any other lipped O O ring static seals one is aware of (seals on injector pump for example).
For the low cost, a set of matched rebuilt injector nozzles would probably not hurt. I would personally remove and inspect every fastener and on re-assembly use copper based anti seize on everything so that in future you dont need to fight rusted and frozen fasteners to do any repair. Take the time to rebuild the alternator and starter so there are no lingering issues..... Take your time and do it properly, you will be glad you did.
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Old 04-09-2021, 15:33   #17
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Re: replace or repair 4.108 perkins 1989

Originally Posted by c.K. View Post
my engine lacks compression turns over quite fast yet ran well for me the past 10 years
Oil analysis good no excessive oil use , no smoke, guess around 3500 hrs
Thinking new piston liners or replace
Just installed new prop shaft etc any suggestions are much appreciated
Thank you
Donít touch it for another 7,000 hrs👌
how long has this been going on and why wasn't I told about it earlier.....
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Old 04-09-2021, 20:57   #18
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Re: replace or repair 4.108 perkins 1989

Originally Posted by skipperpete View Post
Consider adjusting the valve clearances and maybe observing cylinder blow by before diving into a rebuild.
A compression test is gives a good indication of cylinder pressure only...... and no clue to why the compression might be low so try a leakage test as well. You can use the same injector adapter as the compression test and will get a really positive indication of where the compression pressure is actually being lost.
I would definitely check the valve clearance first. That could easily explain a low compression situation.
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