simbasupra Posted March 31, 2014 Share Posted March 31, 2014 Hi guys Just had an engineering company measure my cylinder bores. They have said the cylinders are worn 2 thou over 86mm. I have converted this on google to 0.05mm. Is this correct? That would make my cylinder bores 86.05mm. The manual says to replace the block if over 86.02mm. Is this amount of wear normal for a 100,000 mile cylinder block. Quote Link to comment Share on other sites More sharing options...
Guest Budz86 Posted March 31, 2014 Share Posted March 31, 2014 Is that consistent across all of the cylinders? Doesn't sound too bad to be honest, but I'm no expert. I think you can get a set of piston rings that will make up the difference, or get the block bored to 86.5mm and use a set of aftermarket pistons and do a built block. The key is consistent sizes across all 6 cylinders so the compression is even Quote Link to comment Share on other sites More sharing options...
simbasupra Posted March 31, 2014 Author Share Posted March 31, 2014 Is that consistent across all of the cylinders? Doesn't sound too bad to be honest, but I'm no expert. I think you can get a set of piston rings that will make up the difference, or get the block bored to 86.5mm and use a set of aftermarket pistons and do a built block. The key is consistent sizes across all 6 cylinders so the compression is even They didn't say if it was consistant across all cylinders. However before I sent them the block I measured them and got 86.03 across all cylinders. I sent it to them as I wasn't sure on the accuracy of my gauge and they are the experts. So I assume they got 86.05 across all cylinders. Do you think it would be worth taking it to another engineering company for a third opinion? I didnt realise I could make up the gap with piston rings. I thought I would have to rebore and use bigger pistons. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted March 31, 2014 Share Posted March 31, 2014 If the bores aren't particularly tapered or oval that amount of wear may not result in very excessive oil consumption, or reduced power. May I ask, has the engine been run with a none standard air filter/ they are the prime reason for excessive bore and valve guide wear. As it's in bits you'd be mad not to rebore, cross hatch hone and fit new oversize pistons and rings though. Quote Link to comment Share on other sites More sharing options...
simbasupra Posted April 1, 2014 Author Share Posted April 1, 2014 If the bores aren't particularly tapered or oval that amount of wear may not result in very excessive oil consumption, or reduced power. May I ask, has the engine been run with a none standard air filter/ they are the prime reason for excessive bore and valve guide wear. As it's in bits you'd be mad not to rebore, cross hatch hone and fit new oversize pistons and rings though. Has only ever had standard air filter as far as im aware. The cylinders have worn evenly and not tapered/oval. The reason I took it apart was slight lack of power and low compression on cylinder 4. Out of interest how come you would rebore and fit oversized pistons instead of making up the gap with different piston rings? Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted April 1, 2014 Share Posted April 1, 2014 Stock and high end pistons and rings are designed for a particular bore size. Hand fitted rings that cheaper pistons come with are pretty crude, hand fitting is required because the production tolerances are poor. they are not designed to "take up" bore wear. They still need fitting to a bore of the correct dimensions. A bore with that much wear will NOT be straight, more wear will have occurred at the top one third where side loading on the firing and compression strokes are highest. It wants a re-bore unless you are doing it up as cheaply as possible to sell it. Quote Link to comment Share on other sites More sharing options...
simbasupra Posted April 1, 2014 Author Share Posted April 1, 2014 Cheers Chris So best option would be to rebore to 86.5mm, cross hatch hone, hot wash, then fit oversized pistons and rings. Could you recommended any good value oversized pistons? Also what is the best method of getting the surface properly cleaned up? Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted April 1, 2014 Share Posted April 1, 2014 (edited) Wiseco or JE are OK, and I have used both in 2JZ engines, (and many other engines, too). Mahle had an issue where the skirts were not machined to clear TT oil squirters, which wasn't very encouraging. Maybe this has been resolved now, I do not know. Whoever does the boring and honing should be able to surface grind or fly cut the block face if it needs doing. Don't have more taken off than is vital to achieve a suitable finish. The secret with both these makes of piston is gapping the rings right. I used to hand file them, which is very time consuming, tedious and an acquired art. In the end I bought an expensive vernier equipped, powered ring grinder. Should have done it years ago, it makes the job a lot faster, and is very accurate. I am told there are only two others in the UK, so probably someone will have to hand file them. The power is in the bores and head work, so get it done right! Edited April 1, 2014 by Chris Wilson (see edit history) Quote Link to comment Share on other sites More sharing options...
simbasupra Posted April 1, 2014 Author Share Posted April 1, 2014 (edited) Thanks Is piston ring filing by hand just a case of pushing the rings down the cylinder evenly with a piston, measuring with a feeler gauge, removing, filing, then checking? Do oversized pistons come with instructions stating what the piston ring gaps should be? Also could I reuse the stock conrods with oversized pistons. Sorry for all the questions, I just like to know exactly what has to be done, as never rebuilt a bored engine before. Edited April 1, 2014 by simbasupra (see edit history) Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted April 1, 2014 Share Posted April 1, 2014 You square a ring in the bore, measure the gap, decide from the type of usage options V ring gaps on the spec sheet with the pistons, what gap you need, and hand file. They need to be square, you must not chip any coatings or platings, and of course you must not break one. It is tedious and slow, you can't put material back on if you overdo it Rods can be re used, you may want to fit uprated rod bolts, or new stock ones. The formula for the end gaps is based on bore size, and will be shown on the JE and Wiseco sites. there are probably You Tube videos of ring gapping, if you do a search. The two oil control ring rails per piston should not need filing, they run big gaps anyway, the others will. So that's 12 rings to do. Quote Link to comment Share on other sites More sharing options...
simbasupra Posted April 1, 2014 Author Share Posted April 1, 2014 That makes sense now. Just found the info on the wiseco website. Thanks for your help:thumbs: Quote Link to comment Share on other sites More sharing options...
Swampy442 Posted April 1, 2014 Share Posted April 1, 2014 I think what Chris is saying is do the job right, give the job to him Quote Link to comment Share on other sites More sharing options...
simbasupra Posted April 1, 2014 Author Share Posted April 1, 2014 (edited) I think what Chris is saying is do the job right, give the job to him Shropshire is a bit far, plus I was just unsure of rebuilding and engine after a rebore, so the advise from chris was very helpful. Edited April 1, 2014 by simbasupra (see edit history) Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted April 1, 2014 Share Posted April 1, 2014 I have 2 member's engines here as it is, can't do any big jobs until they are finished. But happy to help then, if desired. One is from Portugal, so Hampshire is a relative cock's stride Anyway, by then we'll all be battened down in fear of Ebola. Quote Link to comment Share on other sites More sharing options...
simbasupra Posted April 2, 2014 Author Share Posted April 2, 2014 Just got off the phone to the engineering company who have quoted me £42 per bore. So total of £252 to rebore all cylinders. Is this price the going rate? I am going to ring other engineering companies tomorrow. Quote Link to comment Share on other sites More sharing options...
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