jetjock;1932209 said:happy mechanics are as common as dirt. ...
Still isn't true with the other qualifiers removed.
jetjock;1932209 said:happy mechanics are as common as dirt. ...
super51fan;2020112 said:I guess this old thread is alive now. The 7M is a great engine.
Looking through the MKIV sections of forums it looks like the 2jz engine that have been worked on are having head gasket issues. This brings me to my point. Most 7M failures are caused by Lack on maintanance IE fluid levels, poor workmanship and assembly errors. IE people not having the common sense to realize 25 ft lbs is way to much for a 8 x 1.25 fastener. Can't even read a TSRM correctly. Or read though it several times before starting on a project.
IMO.
Have a good day.
S.A. supra;2020121 said:I bought 3 supra and they all had bhg. Even the one I bought from a 60 plus year old man. I have been waiting for a mkiv to show up on Craigslist with a bhg but have yet to find one. Guess I'll just keep looking.
Supracentral;1931109 said:Here's a little more info:
The 7M is essentially a very good design with a few caveats.
The good stuff: First and foremost, it's an inline 6. That gives you 7 maincaps for 6 cylinders. That's a well supported crank. The inline 6 is an inherently well balanced design, meaning less stress on the rotating assembly as compared to other designs. One comparison would be against an inline 6 which is not as inherently balanced and only gives you 4 maincaps for 6 cylinders. The oil system is a high volume, low resistance system which works well. The tolerances, machining and balance are all very high end due to this being a product of mid 1980's Toyota technology.
The caveats: The bore is smaller than the stroke, so this (long stroke) motor doesn't take well to high revs as well as a square (2jz) or short stroke (1jz) design. This is a mixed material motor with an iron block and an aluminum head. This means you've got different thermal expansion rates between these two surfaces that are mated together. The bores are so close on a 7M that the cylinders are nearly siamese and there's very little gasket material between them. The inline 6 design unfortunately forces an extremely long cylinder head. You couple these last few factors together and you've got a design that puts a LOT of stress on the head gasket. Add in a little extra boost, an unmetered air leak, the wrong fuel, poorly done modifications or a failure to address small issues before they cause detonation and you're going to put more stress on that gasket than it can handle.
As mentioned, the factory torque spec for the head bolts was long ago determined to be a little bit too soft. Torquing them to the appropriate new values fixes this issue. Upgrading to a metal head gasket with the proper prep of the mating surfaces adds more insurance. High quality fasteners add a little more.
So with all that said, yes this can be a reliable motor, it's an inherently good design with a few weak spots. The primary being that the head gasket doesn't tolerate detonation well. In the end, as I've said hundreds of times at this point; the weak link in the MKIII is usually the owner. If you don't use your head, perform poorly thought out mods, cheap out or skip maintenance and generally act like a complete bonehead, the 7M will hand you a well deserved world of hurt. Only you can decide if you're going to be the weak link, or one of the stronger ones.
If you can use your head, do the correct modifications in the correct order, perform maintenance as needed and pay attention to details, you'll be fine. However you had better be ready to spend money, this isn't a cheap endeavour and trying to do it "on the cheap" just about always ends in failure.
uncmk3nut;2020545 said:That is a good one, I will just tell everybody that "yeah it's a 2j and pop the hood and see if they even know what they are looking at" lol