arnach said:
See this thread here:
Head Gasket DIY
I would recommend replacing the head gaskets on your existing engine if it is in good shape. Mine were replaced at 70k miles and my engine is running perfectly at 160k now. The problem with the JDM engines is you have no idea where they've been -- they really are 30-40k engines most likely due to how things go in Japan -- but theyve often been sitting in a junk yard for several years. Due to the fact that the engines are often scrapped after 30-40k miles they are driven excessively hard and maintenance is not a top priority for them. Im not exactly sure of the owner's experiences here with them, but for other cars, specifically the 300zx -- there have been tons of problems with the JDM motors. The consensus now, at least for that car, is that a JDM motor is NOT plug and play, it is only a basis for a complete rebuild. YMMV but it would make sense to do the headgaskets on the JDM motor before you put it in, along with timing belt and water pump. If you engine has been well maintained and you are good mechanically it therefore makes good sense to replaced the head gaskets yourself.
Horsesh!t. Where are you getting your "consesus" info and what's your point of reference? I've done 2 JDM swaps and in both cases, the engines have been in perfect condition, both inside and out. My tech has taken apart the top side of each engine and says he'd be surprised if they even had 30K miles on them. I know of
no one on here that has done a JDM swap and had problems. Comparing JDM 300ZX engines to Legend engines is not a valid comparison. I wouldn't want a used sports car engine either because it's probably had the piss run out of it. BTW, with the exception of the PAIR (emissions) system, a JDM C32A is very much plug and play. Bear in mind that the reason the Japanese don't keep a car over 30-40K miles is because the insurance and registration become hideously expensive and the junkyards over there are not like what we have here. You have to be bonded and licensed to even walk in one, much less buy parts.
FYI, I was told by an Honda tech specialist out of Atlanta several years ago that there is no permanent fix to our HG problem. First off, we have aluminum blocks with steel cylinder sleeves that are held in place with a ceramic bonding agent. He said that when the block overheats (usually due to radiator failure), the bonding agent begins to deteriorate and eventually fails, enabling the cylinder sleeve to ever-so-slightly move within the block with each piston revolution. Over time, the movement of the sleeve hitting the head gasket causes the HG to fail, 99% of the time at #3 cylinder, which is the furthest point from the radiator in the cooling system. Unless there is some way (and he said there isn't) to "rebond" the sleeve to the block and stop the movement, the HG will just fail again, usually within 50-70K miles. His advice was to either get a get a completely remanufactured short block (about $3-4K) or a low-mileage junker, either USDM or JDM, becuse the original radiators seemed to fail at 50-60K miles. Therefore IMO, unless you have a Jones to do multiple HG jobs, it's probably cheaper in the long run to do a JDM swap. I've had each swap done for under $2K.
I have no reason to doubt what this guy says and this would explain the multiple HG failures that people seem to have suffered. Bottom line, take care of your cooling system and you won't have any problems. But if your car overheats, eventually you are screwed. Period.
