basic questions about engine rebuilding

[Ezookiel]

OK, as you may have seen elsewhere I'm in the middle of having an engine rebuilt that has had a couple of pistons grab in the cylinders after overheating due to a cracked head.

I've seen elsewhere that if a piston has grabbed it may have marked the inside of the cylinder and need honing and relining.

1. How can a cylinder be rehoned without increasing the diameter of it, which would then mean the piston wouldn't fit tightly etc. etc ?
2. What is relining and what is it relined with ?
3. What other things should I get done while it's being done that will be easier and cheaper than having to do at a later date.
4. Anything you can tell me that will make it easier to a) understand what the rebuilder is telling me b) save me being so easily ripped off etc.

Thanks in advance for anything and everything you can tell me.

Trent

[christover1]

A hone is only a light sand basically, rings should take up the small difference.

If a lot is honed out you will need larger pistons, depends on damage.

If too much needs to come out, relining is a steel insert, like shoving a pipe in the bore.

Only takes 1 part to go wrong and whole engine work can be undone.
I'd do what builder recomends. New everything.

I'm no expert, this is just my basic understanding.
None of my home built engines have ever lasted very long
Now I just change donks, let experts build em

christover

[shakes]

1) honing is essentially the same as cleaning something up with a bit of wet and dry, so not taking off enough metal to make the bore size any bigger, just cleaning it up so the rings have something nice to seal against.

2) relining is just pressing out the bit of tube that the piston goes up and down in and pressing in a new one... you get them from the manufactureres or importers.

3) how big is your budget? at the least getting the crank spun is an idea, balancing the bottom end will make everything nicer to drive. open up the valves, new cam etc.. all depends on $$$

4)sounds harsh but buy a manual let us know what motor it is and you'll get some more precises answers too!

Simon

[Ezookiel]

Sorry, didn't mean to imply I'm doing any of this myself.

It's in at QIM engine reconditioners, and some of the things they've mentioned is what has lead to the questions.

I'm told by them that it has "grabbed two of the pistons" and will need honing to remove the damage done by this. He will know more tomorrow when he pulls the sump off and drops ??the cylinders out?? (i think that's what he said, drops something out anyway)

Having seen a previous thread referring to grabbing pistons, they said in that thread that they might need re-lining if damaged too much, so that's why I asked because when I commented on relining he dismissed it without comment, so that's why I wanted to know, cause if it's necessary, then I want it done.
Basically I have NO BUDGET, but since I'm going to have to go to the bank cap in hand, I might as well take as big a cap as necessary and get the job done right. Hence wanting to know everything I can about what should and shouldn't be done to a 4.2 litre diesel Patrol engine with an aftermarket turbo, that is being rebuilt by a company that deals specifically in engine reconditioning, but whose standards are unknown to me and come with one recommendation, and one don't use them comment, so need to know all I can learn so that if the "don't use them" is correct, I can at least keep a semi-literate eye on what is being done and know if it's the right thing or not.

Thanks heaps for the replies guys, you've already told me heaps more than I knew before. At least I know what relining is. The term "re-lining" left me thinking it was some coating or the like that had to be put on, which intriqued me as it would only burn out, so now I know a bit more than before. I love this forum, my knowledge grows everytime I come here.

[cj]

You'll probably find that honing will fix it but if excess wear is detected then reboring is another option. At that point you will need to know the condition of all cylinders and then decide what is more cost effective.

[zookjedi]

next step from honing is to rebore it , obviously needing bigger pistons rings etc to suit .

we (were i work ) use QIM to crack test heads etc small machine work and counter boring blocks in chassis on our engines ranging from 2ltr diesels to 40ltr diesels and we haven't had any dramas so far , and weve used them for at least 6 yrs ,

every were you go you'll gerenerally hear both good and bad reports , i got my own engine work such as cam ground crank linished head and block decked by pro engines in queanbeyan they were cheaper than qim and did a good job and fast , but that was just the parts and machining as i built it myself . i would have no dramas using QIM but pro engines was slightly cheaper and since it was near christmas they were the only mob to guarantee me id have the parts back in time for me to build over christmas

any dramas just ask them why they are doing what they are doing , they should tell you no problem .

cheers Jai

[Ezookiel]

Thanks Jai, that's encouraging.
Cheaper would have been nice, but the main priority is a vehicle I can trust. When you want to take it hundreds of Kms from town, then you also want to know that it'll get home.

[dirtyGQ]

mate if bore damage is too bad you will need new linings pressed in and also a point is that all engine reconditioners state that the injector pump be checked and rebuilt and radiator reconditioned to receive a warranty.
Good luck

[Woop]

Cylinder liners can be honed if required if not excessivly worn. The TD42 cylinder liners are very thin, and its better to replace them if you can. If you have the right tools, and i'd imagine the shop would have, then they are easy to replace. If thats the case, then you just put standard size liners in, with standard size pistons. That way, in theory, the piston to bore clearance SHOULD be correct..

As i've mentioned before, the TD42 is an easy engine to re-build--any competant shop should have no trouble. The most difficult part (and its pretty tricky) is replacing the camshaft bearings. I've attached some pics of my re-build i did so you know what the liners look like and how they fit into the block..

Nick

[Woop]

http://i94.photobucket.com/albums/l114/ ... 00_IMG.jpg[/img]http://i94.photobucket.com/albums/l114/ ... 67_IMG.jpg

[zookjedi]

are they just wet liners ? oppossed to dry sleeves?

[Woop]

The cylinder liners are dry liners. I made up a tool to remove the liners when i did my rebuild. Old ones took lots of effort to remove--new ones went in easily
[/img]

[Woop]

Some more:[/img]

[claud]

hey ,good advice so far ,the best thing to do is go and look at the process as its done in stages without being a pain, maybe bring a coffee or beer for the guy.) u can see by the amount of wear and depth of it what ill need replacing.if your pistons are scored they gotta go.more than 200thou gash in lining of walls and shes stuffed depends on how much .ie the round of it u could get away with a hone if its only deep for a cm or so in length,its not huge strain on compression lossbut wear under load will increase and stress and reheat.so go the new liners .balance up any single piston swaps.ie take another out weigh it and machine the newy to same.