86.5 oil consumption: rebuilt 7MGE

[boogiesurfer]

:1zhelp: This is my first post on this forum. I've been to "car talk" before, and I still can't figure out what's going on with my rebuilt 7MGE. The shop that rebuilt the motor is a transmission shop, and the owner's brother was rebuilding 7MGE's "on the side". I thought $2500 for rebuild and new clutch was a great deal. However, it took them almost a year to get it completed :ugh: I still don't know what kind of rings were installed or any of the technical stuff other than the machine shop "balanced the engine, weighing and balancing rods, etc." When I first took my vehicle to this shop, it took 2 weeks, and it was done. It ran great, but there was one problem, when the motor was cold, and started, there would be a slight "knocking" sound on startup. I took it back, and it took another 10 months before they had it completed! At first the mechanic was scratching his head, and had a difficult time determining where this "start-up knock" was coming from. First thought the heads, and different heads from the machine shop were installed. Still had knock, so they apparently went to the block, and said that the machine shop had not done the crank properly. I should interject here that the original problem was the crank and it had to be replaced, and they didn't utilize my original block, but another block and crank. So when they still had start-up knock, they sent my original block with a crank to the machine shop, and it was finally completed, "balanced", and installed.
Even after all this, they couldn't get it running good, since it was sitting for so long in the shop, and they really couldn't figure out the "electrical" side of things. So I had to take the vehicle to another mechanic to work on the "top end" i.e. wiring harness, electrical components, and found that the computer was fried. My friends can't believe how much I went through to get this Supra repaired and running!
After finally getting it to run well, I realized that I was adding approx. one to 1 1/2 quarts of oil a week (30w). No major smoke, no deceleration smoke (valve guides), and only a "haze" on hard acceleration out the rear (the rear bumper has a thin film of oil after a couple days driving). My new mechanic told me to run 20-50w oil and it could make a difference. It does seem to be consuming a little less oil now, but still 3/4 to 1 qt. per week. Before changing to 20-50w the oil dipstick would always be "popped" out approx. 2-3", and the mechanic said this is indicative of "blow-by". After changing to 20-50w the dipstick many times is not popped out as much, and many times not at all.
I am the original owner of this Supra, and I'll never forget how far ahead of its time it was in 1986. The car runs great, and I'm very happy with the performance, but this oil consumption thing really frustrates me. Is there anything else I can do short of tearing the engine apart again? One last thing, another mechanic pulled the plugs, and said that the #4 cylinder plug was "carbonized". :icon_roll BTW we've done extensive checks for oil "leaks" and found nothing. Thanks so very much in advance for any constructive advice.

 

[Fuzz420]

First let me say welcome to the forum.I had the same problem as you will oil consumption but i had several contributing factors 150k miles,rod knock, etc.The best i could do is run a hotter copper plug to burn up the access oil which made a huge cloud behind my car at WOT.My guess might be the rings.BUT DONT quote me on that.I chose the easy way and just did JDM ge swap instead of rebuild. 3 months and almost 3k miles later she running strong.Also glad to hear your an original owner.Must be nice. :bigthumb:

 

[boogiesurfer]

Thanks Fuzz 420. I just never get hugh amounts of smoke when I "lay on it"; I think, at this point, after this experience, it probably would have been better to just swap out a motor. Live and learn, but I'm kinda stuck with what I got now. I was told that an individual cylinder could be worked on "from the top" and repaired, but I'm not quite sure this is what my mechanic would want to get into :3d_frown: I've probably put 6-7k into this baby including the rebuild, but it's still better than a new car payment :icon_wink

 

[toms_supra]

Hey Boogie surfer, i have the exact same problem as you man. When on startup the engine would make an awful knocking sound then it'll go away but whenever i rev it up to like 3 or 4 grand the knocking sound is always there. I really dont get it at all. Its a whole new rebuilt motor and it does this, im kinda choked. I thought it was a typical thing on these engines since my old one that died did the same problem. It sounds like its low on oil but theres lots there. I just dont get it, im running 5w30 oil. Supra Blues, said it might be an accessory that runs off one of the belts but most of my stuff are new like water pump etc. Does anyone elses 7 mge do the same thing, knocking sound ? Any feedback and help would be greatly appreciated. thanks

 

[lagged]

if the dipstick blows out on your rebuild then for sure the rings didnt seat and thats that. i couldnt think of any other reason.

ummmmm, get a full refund and find a competant shop.

 

[boogiesurfer]

Oh, how I would love to do that, lagged! As soon as the shop realized they were having a problem, they put "six month warrantee" on the receipt :eek3: I certainly wish I could do something about it :icon_mad: Tom supra, I feel your pain guy. I just wonder if you can "isolate" the "bad ring" cylinder/s, and repair this with motor in place, removing head :icon_sad: Would this be cost prohibitive, or can one "live with" this sort of thing; BTW performance is great :icon_excl Oh, also BTW the shop told me that they finally found that the crankshaft "wasn't done correctly" by the machine shop, and that was the reason for the start-up knock. I have no start-up knock since the motor was finished, however the oil consumption is a continual problem.

 

[IJ.]

If they put "Friction Modified" oil in it right away it won't seat the rings full stop!( a good single weight oil with no friction modifiers or viscosity index improvers is a must in the 7M as the cast iron in the block is very hard)

As for pulling the head to repair it in place it's just not worth the extra hassle, much easier to pull the motor and fix it correctly in the long run!

 

[boogiesurfer]

Thanks IJ, that clears up a lot! I can remember that this shop put "Lucas oil stabilizer" in the newly rebuilt motor. Would it do the same, like you're stating? Thanks for all your help.

 

[lagged]

eh you go back and tell them the rings didnt seat, tell them you want them to put straight 30 or 40 weight oil in there. if the motor isnt knocking then at least you know (with some certainty) that the bearings are all ok and thats half the battle right there.

 

[IJ.]

Don't know anything about the Lucas Product you mentioned!

The bad news is that the damage is done and the bores are glazed (Edges of the Crosshatch Hone marks are smoothed over and it's these that allow the Rings to mate to the Bore during breakin)

Not sure how you're going to jump at this but if it were me I'd Drop the Motor Strip it and use a Toilet Brush Hone to give it a quick Cleanup then reassemble it making sure the Ring end Gap is correct.

 

[toms_supra]

So i should go back to the place where i got the motor and say i need another better rebuild motor. I still have the warrantee, its been only 2 weeks since i put in this rebuilt engine. Its weird too, the spot where i put my dipstick in is not the same as the old spot, this new spot is up in the front more and my old motor the dipstick was right beside the exaust manifold pretty much. It's fucked up.

 

[lagged]

um dude. i would get your money back. get a rebuilt motor from PIONEER or someone if you cant find a worthwhile shop in your area.

 

[boogiesurfer]

Toms Supra, absolutely go back and make them honor your warrantee :icon_excl At least you have It :bigthumb: There is no way you should accept a rebuild with a knocking condition.