Engine and drivetrain swap - RD28T to TD42

I think the compression readings are OK, and I think they will be better with valve adjustment too.

My opinion is to go for it, and your mechanic will most probably offer his advice too, but the TD42 is fairly bulletproof, and the old Silver-tops were the pick of the NA Version too.

Thanks mate for the input. I'm having the mechanic adjust the valves today and then retest, so I'll update on the findings when I get the new readings.

Quote:

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Originally Posted by SiberianPatrol

Yes it was hot/warm. Wasn't it supposed to be?


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Yes mate supposed to be warm/hot. Just checking that's all.


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Quote:

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Originally Posted by SiberianPatrol

Ok, in the process of having the diagnostics run on the 4.2 I am considering swapping in. Here are the numbers:

Compression
1 = 25 bar / 362.59 psi
2 = 27 bar / 391.6 psi
3 = 29 bar / 420.6 psi
4 = 29 bar / 420.6 psi
5 = 23 bar / 333.59 psi
6 = 25 bar / 362.59 psi

According to the manual, the compression should be 29.4 bar / 427 psi with a minimum of 24.5 bar / 356 psi and a difference of 2.9 bar / 43 psi between cylinders. That makes cylinders 1&6 on the low end, but within reason but 5 is lower than the minimum. The guy has never regulated or adjusted the tappets/valves and lifters, so that could adjust the numbers slightly higher on the low cylinders.

It cranks perfectly when hot and supposedly cranks well in the cold, but obviously by the time it got to the shop it was hot, so hard to test that one. Mechanic pulled the dipstick and checked for exhaust back pressure to see if the pistons were excessively worn. It had a little exhaust gas come out, but nothing serious he said - acceptable and average for the age and kms on the engine.

I would like some input from the gurus here with the TD42. Is it worth dropping in this engine with the compression readings that I posted? Or am I asking for more trouble later on down the road in the form of a rebuild if I put this one in? Asking for advice here.

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Hmm it doesnt look good. You have a couple in the lower end of the spec not to mention you are well out on the max spec of variance across cylinders. Hopefully the valve adjustment sees some gain otherwise leave it alone. You could also ask the mech to do a leak down test.

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Originally Posted by nissannewby

Hmm it doesnt look good. You have a couple in the lower end of the spec not to mention you are well out on the max spec of variance across cylinders. Hopefully the valve adjustment sees some gain otherwise leave it alone. You could also ask the mech to do a leak down test.

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He just sent these results. Test done on a cold engine after adjusting the valves and lifters. He is warming the engine up now and will retest when up to operating temp

1-24,5
2-24,5
3-24
4-24,5
5-24
6-25

Looks more promising but will wait for the warm engine results.


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Numbers dropped off when the engine was warmed up. Compression dropped to 23 in some cylinders. Mechanic did a wet test and the promptly rose, thus indicating at a minimum a piston ring problem. Will try to negotiate the price down with the seller, but if he won't budge on the price, this one is a no-go for me.


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Bugger mate, sounded promising. Very rare to get a silver top with that low K's over here, would of thought it checked out really well.

Yeah it sounded like a good offer, but I can't ignore the diagnostic results. If I can get it cheap, I may still buy it and overhaul it, then drop it in.

Bummer Mike how scarce are the 4.2s over there?

4.2s can be found, because there are a lot of swaps from the ZD30. Almost every Patrol you see with a 4.2 is a swap. Very rare to find one with a factory 4.2.

It honestly doesn't matter too much where you buy a used TD from. More than likely you will have to rebuild it. There are many companies which offer engines from wreckers, or direct parted out from Japan, but quality is always a question over here.

A good friend of mine bought a "contract" engine (as they are called here) and while it checked out ok on the stand, he still had a boatload of problems with it.

The guy who offered me his 4.2 is an acquaintance and he runs in the Patrol Club over here. He has offered the complete drivetrain to swap into mine - engine, gearbox, front and rear diffs. For that reason I am willing to negotiate with him so that I don't have to hunt down diffs to match the TD gearbox. Still in talks with him about it, so we'll see what happens.