Radiator? Air pockets? Or leaking MHG?

[s turbo 87]

Okay, I just got my car back together after doing a HG job on it, I used an hks 1.2mm bead type gasket. My problem is, the car will run and idle for 30+ minutes without overheating, and driving normal without boosting much at all it wont overheat either. After you boost on it a little bit or go WOT, the temp starts to rise, not all the way up, just slightly above the halfway mark and then the overflow starts to get pissed off and starts gurgling and overflowing. I tried last night to burp the cooling system and it helped (had the front of the car jacked about 2.5-3ft in the air), all last night it was fine and I reamed on it pretty good a few times. It was also pretty cold last night (in the low 40s or high 30s). I got in it today and drove around until it came up to temp and it was fine, I hit 10psi a few times and about 3 or so minutes later, the temp started to rise again and it started gurgling and overflowing again. I'm only wondering about the radiator because it was fine last night and it was very cold outside, but today its warmer (60-65*) The radiator I'm using is a stock rad. and seems to be very old.

side notes: t-stat is a new 180* fail safe, waterpump is new as well.
When I did the HG, I used a new/rebuilt head, but did not get the block machined..i cleaned it very well and checked for imperfections and uneveness on the block deck, but it seemed to be okay. I also have ARP head bolts torqued to 85 ft/lbs w/ARP's Moly-lube.

 

[Allan_MA70]

did not get the block machined..

BBBBZZZZZZZZZZZZZZTTTTT

its been said many times, if your not going to surface the block, Fit a new Toyota gasket not a metal! :nono:

 

[jdub]

I hate those failsafe thermostats...I've had nothing but problems with them sticking. Your radiator could be a problem...if it's partially blocked, it will cause what you describe. You could also have a small leak somewhere allowing air into the system.


Did you use a spray sealer on the MHG?

 

[s turbo 87]

did not spray anything on the mhg...it was new and ive heard to not spray them with anything when they are new....
i just did some more investigation and i noticed that it seems like the radiator might have a small leak on the bottom passenger's side.
I'm going to swap radiators and see what happens i guess.

 

[Mr.PFloyd]

BBBBZZZZZZZZZZZZZZTTTTT

its been said many times, if your not going to surface the block, Fit a new Toyota gasket not a metal! :nono:

i agree with allan. especially withourt sprayign brake quiet if you didnt resurface... i think you got another bhg bro..

 

[s turbo 87]

i think its sorta hard to blow a mhg...maybe leaking if anything, but im leaning towards the radiator at this point..im at least trying to remain optimistic anyways

 

[Mr.PFloyd]

i think its sorta hard to blow a mhg...maybe leaking if anything, but im leaning towards the radiator at this point..im at least trying to remain optimistic anyways

well blow/leak in my eyes is exactly the same, if you dont change it now then it will make it even worse.

 

[jdub]

did not spray anything on the mhg...it was new and ive heard to not spray them with anything when they are new....
i just did some more investigation and i noticed that it seems like the radiator might have a small leak on the bottom passenger's side.
I'm going to swap radiators and see what happens i guess.

It's good you didn't spray the new MHG...you were correct...it has a factory coating to effect the initial seal. Spraying a new MHG is asking to blow it.

That radiator could very well be your problem...the 7M cooling system is very finicky. Change the cap while you're at it. You can get a CSF dual core aluminum direct fit radiator (almost twice the capacity) for around $300...worth every penny IMO.

 

[s turbo 87]

everything besides the radiator in the cooling system is new...where can I find this CSF dual core aluminum direct fit radiator?

 

[jdub]

Got mine here:
http://www.coolradiator.com/HPAToyotaSupraTurbo2.htm

Looks like they are on backorder though...and, I think you would be able to beat this price.

 

[JonoTurbo]

I have to say that the I have a CSF dual core and it definitely cools very well but i'm frustrated with it's design. The upper hose connection comes in at a higher point than the radiator neck. This causes air to get hopelessly trapped in the upper radiator hose. If you really want to get all the air out of your cooling system you may want to consider another radiator.

 

[suprra_girl]

BBBBZZZZZZZZZZZZZZTTTTT

its been said many times, if your not going to surface the block, Fit a new Toyota gasket not a metal! :nono:

agreed!

 

[jdub]

I have to say that the I have a CSF dual core and it definitely cools very well but i'm frustrated with it's design. The upper hose connection comes in at a higher point than the radiator neck. This causes air to get hopelessly trapped in the upper radiator hose. If you really want to get all the air out of your cooling system you may want to consider another radiator.

I have to disagree this this. I have no problem with air in my CSF...it works far better than stock and is cheaper than comparable radiators out there. It's not as pretty as a Fluidyne or PWR, but works just as well.

 

[JonoTurbo]

I have to disagree this this. I have no problem with air in my CSF...it works far better than stock and is cheaper than comparable radiators out there. It's not as pretty as a Fluidyne or PWR, but works just as well.

For the sake of argument, and because i'd really like to know; how do you get the air out of the circled area?

The radiator neck is so much lower and bubbles don't exactly float down. I can get some out by squeezing the hose, but it seems pretty hopeless.

 

[jdub]

I don't

Air at the top of the radiator is not going to effect the cooling system...you are going to have some air in the system. That hump keeps small amounts of air right where it belongs...at the top of the radiator, out of the core, and out of the block.

The ability of the supra cooling system to pressurize is what's really important. If you have a leak (or other source of gas...like a BHG) that allows large air bubbles to form in the system and to displace coolant to the extent it causes the rad to overflow into the coolant resv...then you have a problem.

 

[bigaaron]

See the hose to the left of the circled area that goes to the overflow bottle? If the cooling system is working correctly it will suck in coolant from the overflow bottle the first time it cools down after running and displace any air in the system. All you need to do on a 7m is fill the radiator full, let the engine run till it gets up to temp with the cap off and make sure it is full, then make sure the overflow is up to the correct level. You should not have to "burp" the system. Metal headgaskets usually fail by leaking, but that would basically be considered blown. After spending any more then an hour on this site I would think that you would get the idea that not surfacing a 7m deck for a mhg is a very bad idea.

 

[jdub]

BTW - Aaron and the other guys are correct...you should have re-surfaced the block if you're going to use a MHG. I actually missed that :3d_frown:

Installing a MHG without decking the block to the proper RA spec is a crap shoot at best on if it will hold up or not.

 

[s turbo 87]

yeah, i know i was supposed to get the deck resurfaced..and i would have done it, but im a poor broke bastard and i was taking a chance...im almost sure the hg isnt leaking and if it stops raining today i will know for sure when i swap radiators...thanks for everyone's input.

 

[starscream5000]

I'd say the hg is probably blown. It's a good thing we pulled in behind you last weekend on the way to the chinese place or you would have been stranded. My cousin (the guy that bought your old head, thanks BTW) did the same thing as you. Resurfaced the head, didn't do the block, slapped a MHG on, BAM! BHG like 300 miles later. It's a cruel world...

 

[s turbo 87]

I'd say the hg is probably blown. It's a good thing we pulled in behind you last weekend on the way to the chinese place or you would have been stranded. My cousin (the guy that bought your old head, thanks BTW) did the same thing as you. Resurfaced the head, didn't do the block, slapped a MHG on, BAM! BHG like 300 miles later. It's a cruel world...

the only reason why i think it isnt the head gasket is because i had an old radiator on the car when i first got it running and it never had this problem, but then it started leaking from where someone who had owned it before me was a little rough with getting the lower hose off...then i put this other used radiator in there and found out that its leaking also, seems to be a small pinhole somewhere on the lower passenger's side. I'm going to pick up yet another radiator today so hopefully i will know tonight or tomorrow if I'm having radiator woes or hg woes. I shall remain to be optimistic about this before I rip the head off and my car is down for another 7 months.