Need help with a overheating issue. out of ideas...

Nick M

Nick M

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Sep 9, 2005
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jetjock said:
"However I still stand by my statement that 99 times out of 100, the weak link in the MKIII is the previous owner."

Fixed ;)
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"Time to jack up the radiator cap and roll another one underneath it"
:biglaugh:

That one is an all time classic for this site.

edit: One other thing is, I have seen a headgasket installed upside down. When the passages get blocked, the temps will spike.
 
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we'll see. I'm naturally hoping its just air stuck in there. if it is a BHG, its just another thing for the list.

I'll hafta get some pics up, this car is a 9/10 as far as original body and interior go. one of the nicest un-molested 20 yr old car I've ever seen. I bought this as a project, getting away from VWs and am going to try and make some good power (4-500hp) on somewhat of a budget. So the car will be parked for a while at my work, so if it is a BHG, its not devastating, just another thing to do / learn how to do on this car. I'll make a post tomorrow in the appropriate forum with some pics and my plans.
 
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IJ. said:
Budget/500rwhp hmmmmm ok ;)
(now if you said Big Budget/500rwhp that's another matter)
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I got this pile of goodies off ebay for $600
f8d7_2.JPG


a couple grand is a fair budget I think to make 400, maybe 5. we'll see, I'm good at finding stuff for cheap and doing my own labor ;)
 
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IJ. said:
LOL I wish you the very best of luck in the project! :D
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maybe I'll spend more or not make as much power, I'm just out to have some fun, I like to set high goals. I have good connections for parts and whatnot too.

I'm new to supras, but not cars. my last project was a 13.5 sec n/a rabbit :)
 
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Nick M said:
edit: One other thing is, I have seen a headgasket installed upside down. When the passages get blocked, the temps will spike.
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I never thought of that. I actually wouldn't put that past the guy I got this from. but I can't complain of the thousands he spent in new dealer parts he got for it, then sold it to me for 1500 ;)
 
mkiiSupraMan18

mkiiSupraMan18

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If this is for a big hp build, why not just go ahead and tear it all down now?

Not like the engine will last long being overheated all the time.
 
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mkiiSupraMan18 said:
If this is for a big hp build, why not just go ahead and tear it all down now?

Not like the engine will last long being overheated all the time.
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I want to get it running at 100% with no issues before I start building it up. since its a lower mile engine, and has a new metal HG I was hoping to not haver to take the head off.


so today put a thermostat in, burped the system fairly well, did 20 min of hard driving and it started to heat up some and gurgle, but not as bad as before. so I'm going to try burping it again for the hell of it, and get one of those kits to see if theres exhaust in the coolant. I'm just resistant to think a brand new metal head gasket could start leaking after one day, then again, it could have been a shitty install.


whats the likelihood that a engine with 80k thats well maintained and stock could have a cracked head or block? that would be something I'd have a hard time dealing with at my shop.
 
jdub

jdub

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Well, unless the head/block deck was machined to the RA spec required for the MHG...it's very possible it did not seal. See it all the time with guys trying to cut corners by not pulling the block and having it machined for a MHG. The NAPA block tester should tell you if exhaust gas is in the cooling system...if there is, it's a BHG.

Not likely the block or head is cracked...but then again, if you have it apart, I'd have it checked!
 
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jdub said:
Well, unless the head/block deck was machined to the RA spec required for the MHG...it's very possible it did not seal. See it all the time with guys trying to cut corners by not pulling the block and having it machined for a MHG. The NAPA block tester should tell you if exhaust gas is in the cooling system...if there is, it's a BHG.
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thats probably it then. I know he strait edged the head and block and said they were fine (to my knowledge is ok for a normal HG) I wasn't, and I'm sure he wasn't aware you HAD to have the head and block machined for a metal HG, however, it makes sense now that I think about it.
argh.


now my question, is there a way to machine the block IN the car? heh. or is there a way to check to see if it needs it for sure? (I'm sure the head will) I don't really have the ability to pull out a block.
 
jdub

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Nope...you gotta pull the motor. All you really need is a cherry picker...Harbor Freight has a folding 2 ton unit that's pretty reasonable. Of course, an engine stand makes life easier ;)

The other alternative is to go with a stock Toyota composite HG...you can boost to fuel cut (~14 psi) no problem with ARP hardware torqued to ARP spec. You do have to make sure the block/head decks are flat and all previous gasket material completely removed. As you alluded to, you don't have to pull the motor...assuming the block deck is in TRSM spec flatness wise.

Keep the MHG...it's re-usable.

The other thing to consider is did coolant get into the oil. If it did, coolant does a number on the bearings pretty quickly. Take a look at your oil cap...is there a milky deposit? If so, that is coolant being emulsified with your oil...not good. It is a very frequent occurrence for rod knock to follow a fixed BHG because of coolant getting into the oil. If it were me, and I saw that coolant got into the oil pan, I would pull the motor and change the bearings at minimum. What you would have to decide is how far you want to go re-building it ;)

BTW - it is a very good idea to run this motor a quart of oil above full.
 
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the oil looks fine, one of the first things I checked.
my shop does aerospace, hydroplanes, dragser wings, ect.. mainly composites. we do have precision measuring equipment I can use to check the block, I just need to look up the tolerances. the head I can hand to my machinest no problem.

once I get the head off, (presuming it is a BHG, I'm not giving up hope yet, heh) I'll check the block and if it needs machining, if it does figure out if if I'll be happy with 14lbs of boost, (even tho I have a T84 turbo on the way) or if its worth pulling the block.

either way, I got a $1500 supra with a near perfect body and a 9.5/10 interior with a newer japan spec engine, I'm still happy with it :)


thanks a lot for all the info everyone, once I get past this overheating / BHG shit, I'll start a build-up page and take lots of pics
 
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jdub said:
NP man!
Now that you own a nice platform for a build..."Open door, insert copious amounts of cash"

Here's one more piece of the puzzle for ya...until you get your own TRSM ;)
http://www.cygnusx1.net/supra/techtips.aspx

All the specs you will need.
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already have that paged bookmarked ;) I've got a hook-up at a toyota dealership service department, I'll see what I can pull off. I have a feeling I'll be pulling a lot of favors through him soon :)


according to the TRSM block surface needs to be within 0.0020" of flat, which I can measure. I'm just going to go ahead and pull the head and have it machined for sure. even if it turns out its not a BHG, it probably will blow with more boost since he never had anything machined.
 
jdub

jdub

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If you got the cash, might as well have the head freshened up ;)
3 angle valve job, new seals, check guides and springs...have the head decked to the lowest RA the shop is capable of. 30 RA will cover any MHG out there.
 
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