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Discussion Starter #1
1988 TB42, blew the head gasket on #6, now trying to see where to go with repairs.

I need to decide whether it's worth to do the head work, and that depends on if the bottom end is worth keeping. Bought the truck two weeks ago so don't know the history much. Engine ran strong and smooth without any apparent issues.

Here's the cylinder compression numbers:

#1 160 psi
#2 150
#3 140
#4 150
#5 110 (140 with oil)
#6 splashing out coolant LOL

The manual says minimum is 128 and standard is 171. Also says the difference between cylinders can be 14 psi.

So, your advice - would you go ahead and replace the head on this block?

The numbers are good on the first 4 cylinders, though the difference #1 and #3 is a bit more than the given 14... but the worry is that #5 comes in real low at 110 though perhaps it's because of the head gasket in the adjacent #6?

It did jump up to 140 with adding oil, which is supposed to indicate worn piston rings :(

I can do the head gasket at home, but I can't pull the engine.
 

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The big question is can you get the parts, and how much it will cost you. In Australia, you would be looking at approx AUD $1200+ for the parts (head, gaskets head bolts and the bits.)

You may be extremely lucky and change the head gasket only, but you should do the job properly.

You can remove the head insitu without touching the bottom end.

The problem will be a water gully corroded at number six and probery the gasket between 5 & 6 - do a search as I have seen post on this issue
 

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Discussion Starter #3
Parts are ok as we have plenty of Patrols here. We have a selection of originals, good copies, bad copies, then also plenty of used parts: good from scrap, not-so-good from scrap, etc.

The issue here is the workmanship. That's the problem. Filthy workbays and wonky tools, engines left in the open to gather dust while parts arrive, re-using parts that belong in the bin, etc.

Or there's the dealer's workshop, but that's $$$.

I've got space, tools, and I'm fairly confident I can do it properly. I have the downloaded manual, and the Haynes is on its way.

You reckon the bottom end is ok with those compression results?
 

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Pull the head off and have a look anyway. You'll soon see what the issue is. The head will no doubt need some work done to it. Its not just as simple as replacing the head gasket. You'll need to get the head crack tested and repaired. These things are notorious for cracking between the valves. It cost me 2k to do it myself two years ago. But. I did buy a reco head. Because it was going to be about the same cost to repair mine.
As for the cylinder pressures its kinda coincidental that the pressure is so low in five when six has coolant in it. Mine went between 5 and 6 as well.
You really don't have much to loose pulling the head off and possibly dropping the sumo to pull a piston and rod out.
 

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Have a look at your exhaust pipe - if it is full of black soot then consider doing the bottom end.

Also once you have pulled the head - if there is a high soot build up consider doing the bottom.

I was very lucky and picked up reco head for $300 when I done mine last year,
 
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