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1995-2002 Range Rover P38A
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Discussion Starter · #1 ·
Hello all,

I am new to the forum, and am looking for some advise with regards to an engine rebuild. I recently bought a 1999 P38 HE with a seized 4.0L Bosch engine (odometer reads at ~150K). Fyi; I bought a 1999 LR Disco new 16-1/2 years ago, and am still driving it daily (cyl heads rebuilt and new cam). But I always wanted a P38 as well.

I have disassembled the engine and found that the #3&4 rod bearings were cooked/melted to each other and to the crankshaft. It looks like nobody ever changed the oil in this thing; there was thick crusted oil sludge on top of the cylinder heads and in the oil pan. The pistons would barely rotate on their wrist pins. Its in bad shape.

I am planning on replacing the crank (already sourced), cam, connecting rods (already sourced), pistons, etc... and turning in into a 4.6L (longer stroke crank, with associated 4.6L rods, piston, and cam). I am not sure what to do about the cylinder liners though.

Question:
Can the cylinders warp into an elliptical shape if the engine overheats too much? The reason why I ask this is that the horizontal diameter measurements are less than the lower value of the range indicated in the LR shop manual (94.00 to 94.04 mm). I am getting horizontal readings down to 93.87mm (averaging 93.91mm); 7 out of 8 cylinders have horizontal measurements less than 94.00 mm. The range of vertical measurements that I am getting is 93.98 to 94.04 mm. The maximum ovality allowable per the LRSM is 0.13mm; I am only barely exceeding this on one cylinder at 0.14mm (and considering the tolerance of my measuring devices and potential operator error, this is close enough).

The warpage does not seam to be associated with wear; there are no noticeable ridges in the cylinders at the top or bottom of the piston travels. The cylinder liners do not look like they have moved at all (no evidence of slippage).

I am strongly considering just doing a quick hone to break the glaze and putting new stock pistons/rings back in it with the existing liners. But if there is warpage and the decreased horizontal measurements would cause excessive friction and potentially binding, it may be prudent to install new top hat liners. But this would be expensive and I don't want to do it if it is not necessary.

Does anyone have experience with this issue? I would appreciate your thoughts and advise.

Thanks,
James
 

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1995-2002 Range Rover P38A
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12 Posts
Discussion Starter · #2 ·
LOL, already replying to my own thread!

I was talking to a guy at a machine shop who had a reasonable thought. He said that the smaller than anticipated horizontal cylinder diameter measurements could be due to not having the cylinder heads torqued down. He said that a torque plate should be installed to get accurate measurements.

What do you all think?
 

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JACK'S GRANDAD
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9,248 Posts
I measure runout for customers, and just before I drop a block off to be machined to make sure the 20 over pistons I put in EVERY engine I build are going to work. Not had one yet that wouldn't take the pistons.
Are you saying you are going to all that trouble, to put used pistons in it? If new, surely you'd go 20 over and KNOW it's right? Oh well....
And the torque plate doesnt affect a thing on these engines.

Martin
 

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1995-2002 Range Rover P38A
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Discussion Starter · #4 ·
Hello Martin,

I am putting new HC 4.6 pistons in it. I just ordered a full engine 4.6L rebuild kit from Rimmer Bros; it comes with pistons (although standard size!?!?), cam, cyl head rebuild parts (valves, springs, guides, seals), rocker rebuild kit, crank bearings (0.010" over), etc.... I previously sourced new 4.6L connecting rods from Turner Engineering (cheapest price around for new OEM rods). And I sourced a 4.6L crank from a salvage yard; it is in pretty good nick, but I am off to the machine shop tomorrow to get it turned down 0.010".

I was either going to replace the cylinder liners with top hat liners or have them bored if they were too far out. But they look better than I expected. There is no visible wear, no ridges, and no evidence of slippage (heck, the cross-hatch honing marks are still visible!). The measurements do not look too bad either, except for the narrower than expected horizontal measurements (??? scratching my head ???; maybe my measuring equipment is not so accurate or it could be operator error, or it could be warped due to overheating???). The average vertical measurement is 94.0025 mm (within tolerance); the average horizontal measurement is 93.9138 mm (too small!); and the average ovality is 0.0888 mm (within tolerance). The liners are not very thick (~2 mm or so), and I am worried that if I was to have them bored out, they may weaken and start to slip (i.e. don't fix it if it ain't broke!).

Any ideas as to why the horizontal measurements are small? Would overheating cause something like this? Ideas?

Thanks and regards,
James
 

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JACK'S GRANDAD
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9,248 Posts
Wait until the bearings arrive before grinding the crank. Without knowing the make of the bearings, I wouldn't bet a crank on them being right.
Every motor I pull apart still has the cross hatch marks in it, and no ridge to speak of. Junk rings from LR that dont seal very well. Hell it's a bonus having the rings in there right, they had a lot of motors that got swapped due to the rings being in wrong and burning a load of oil.....
You can bore them out no problem.
If the engine got hot enough to seize, it is a good candidate for top hats. I have yet to see a motor that wasn't completely cooked, have a liner issue. But with yours being seized......I wouldn't trust it myself.
Why did you go overseas to get the rebuild stuff? Only thing I get from there is pistons. Rings are from here, as with everything else

Martin
 

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Discussion Starter · #6 ·
Martin,

Thanks for the heads-up on putting 020 over pistons in it. I have checked around at a couple of local engine machine shops (brought the block to them for a look), and they both have said they can bore it, no problem; and the cost is not that much. Also Rimmer Bros said they would switch out the standard size pistons, in the kit I ordered, with 020 over pistons for no additional cost. I think this is the prudent thing to do considering that there may some out of round issues, and that I am putting in a longer stroke crank and the pistons will be traveling farther into virgin area.

As far as going overseas for parts; I shopped around and went where I found the best prices.

Regards,
James
 

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Don't jump in and get the boring done until you have the pistons in your hand. Different piston manufacturers can have different piston/ bore clearances specified, so a good machine shop will want to measure your pistons and bore to the correct clearance.
 

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JACK'S GRANDAD
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9,248 Posts
Do yourself one BIG favor then.
Have the shop hone it for chromoly rings, and get a set of Hastings rings for it, fro over here.
With all the bearings, a performance cam kit from Crower, all seals, good pistons and rings, oil pump gears, custom rocker shafts and end supports, I have under $2k in parts. I could do a "stock" build for less, but not by much, maybe $500.
My issue is, if I run into a problem on a customers engine, I need replacement parts within a day or two. I can get that from my supplier over here.
 

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Discussion Starter · #9 ·
Thanks for the replies.

I am going to wait until I have parts in hand before the machining commences. I will bring the new pistons and crank bearings to the machine shop for measurement, manufacturer instructions, etc....

Another topic:
The 4.0L P38's came with a ZF4HP22 transmission, where the 4.6L came with the stronger ZF4HP24. Since I am stroking the engine to a 4.6L should I be thinking about a transmission swap, or will the ZF4HP22 be good enough? There are a couple of ZF4HP24's at local salvage yards; I could pick one up and throw a rebuild kit into it, but it is a fair amount of additional expense and work. Thoughts?

Regards,
James
 
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