Help...Confusing coolant problem

[Whasian]

Ok, I just finished a rebuild after a bhg, Everything changed. Every hose and every gasket is new. I have a mhg with arp hb torqued to 89 ftlbs. The car is boosting normaly (but there is a crack in the downpipe so I have a new one coming in on friday) I first put water in the car to make sure that there were no leaks in the cooling system, and there were none that I could see but I kept losing the water out of the resevior so I called a few people and decided to put the coolant in the car aftre concluding that the water was boiling at a lower temp causing steam to disipate.

So I put toyota red coolant in the engine, radiator, and resevior (mix to about a 65/45 ratio) and started the car, Everything went great, the heater was working full blast and nothing was going wrong so I drove the car for about 15 to 20 minutes puting the engine though it's paces. I stopped a couple of times to look at the resevior and it was still at the full mark. But after it started getting dark, the "birdcage" light came on and I checked the resevior and sure enough it was empty, so I filled it and drove again. It did the same think within about 5 or 10 minutes.

Does anyone know where my coolant could be going or where it could be leaking from? I am open to any ideas. 2k8 is Tomorrow and I can't take my car if I don't figure this out...PLEASE HELP!

Whasian

 

[adampecush]

did you replace your radiator cap?

 

[eman2289]

I first put water in the car to make sure that there were no leaks in the cooling system, and there were none that I could see but I kept losing the water out of the resevior so I called a few people and decided to put the coolant in the car aftre concluding that the water was boiling at a lower temp causing steam to disipate.

Re-phrase that.

You keep putting coolant in the car, but it is disappearing?
Are you filling the radiator while the car is cold and facing upwards on a hill? Do you have the heat on full blast? I don't understand why you are filling the reservoir.

 

[jdub]

It's going to take a bit for all the air to cycle out of the system...this assumes the rad cap and thermostat is in good shape. The rad should pull coolant out of the resv when it cools down.

A couple questions on the HG job:
- You torqued ARP bolts to 89 ft/lbs using moly as lube?
- Was the block AND Head decks re-surfaced for a MHG?
- Did you lay the MHG on the block deck and check if any of the rivets touched the deck?

 

[Whasian]

yes, the radiator, the cap, and the thermostat are all good. The heater works great, a lot of heat come out of it and the temp guage never moves from the right spot. the reason I am filling the resevoir is becuase the light is coming on and it it low.

whasian

 

[Whasian]

Sorry, The head and block were also in great shape and were resurfaced. I used the grease that came with the head bolts for lube and no rivets were touching the surface of the block or head.

Whasian

 

[jdub]

Is the resv pushing coolant out the over flow, or is it pulling the coolant into the rad? If the latter, is it happening when you shut the car off?

Have you pressure tested the coolant system?

BTW - you over torqued those ARP head bolts by 19%
ARP spec for head bolts on an aluminum head using moly for lube is 75 ft/lbs.

 

[adampecush]

eh, my ARPs (bolts) are torqued to 90 lb-ft with no problems in 60k kms, so I don't think that is too big of a deal.

 

[jdub]

Only if you think the ARP engineers have NFI what they are doing...I guess ARP saying "Do Not Over Torque" is put out for some unknown, BS reason that should be routinely ignored. What's the point in over torquing? You are cutting into the 25% yield strength safety margin ARP has spec'ed for their hardware...which, considering the expansion rate for aluminum on a steel block, is there for a very good reason.

How about just using ARP spec's as intended...it's plenty to keep a MHG sealed. That way there won't be all these torque numbers floating around people just pull out of their arse...especially when they're doing it having NFI of what the impact is (like you).

 

[adampecush]

(I wasn't the owner of the car when the motor was built, I just have the build spec sheet here...and was speaking from the experience I had)

That, and being a materials engineer myself, I have some idea what I am doing. But I suppose that doesn't really matter...

 

[jdub]

Then you, of all people, should not be saying that a 19-20% over torque on an aluminum head is "not a big deal" :3d_frown:
You should also know that the lube used has a big impact on the torque value as well.

 

[adampecush]

I am aware of the effect of lubrication on the torque. As far as I'm concerned, if the tightening sequence is followed correctly, the head is robust enough that no local deformation will occur with a moderately higher clamp load. Also, 20% more torque does not translate to 20% more preload as the coefficient of friction within the threads is rapidly increasing at higher loads.

 

[jdub]

Ok then...How about 100 ft/lbs? More is better, right? Heck, lets go to 120 ft/lbs

I hope you see my point. And it's not the preload that's a problem...it's expansion from heat that aluminum experiences vs steel that causes a deformation/warping and causes the bolts to stretch.

These heads are not a robust as one would think...warping from heat is common even at stock torque values.


Time to get back on topic

 

[adampecush]

I certainly see your point, and yes, uneducated "guesses" usually end up with dire consequences. back on topic indeed.

 

[Shima]

can u smell any burning coolant? u know that horrible smell. and maybe the leak is around the firewall? even when i tightend my heater valve thingie < thats a technical term mine still leaked a bit which anoyed me and resulted in a new pipe. just an idea

 

[3p141592654]

Here's a real simple test. Squeeze the upper rad hose and check if any coolant flows into the reservoir. If it does, you have a bad or incorrect rad cap (there are two caps, and the 90+ cap does not work with the older style 86-89 rads. All aftermarkets I've seen use the old style cap. Hope its this and not something worse.

 

[Whasian]

eh, my ARPs (bolts) are torqued to 90 lb-ft with no problems in 60k kms, so I don't think that is too big of a deal.

+1 All of the supra owners in Northern California with 7m's and the few 7m owners here in Houston are setting the torque between 85 and 90 ft/lbs.

Whasian

 

[Whasian]

Thanks to everyone for the advice...(including the small disagreement about the head bolts) I have check everything that everyone said and found nothing wrong any of those things.

However I did find the problem and it was an easy fix. the 90 degree hose that comes off the union bolt on the back of the head and attaches to (what I call) the coolant bar the wraps around the motor was not tight enough. I was looking around the engine and smelled the coolant leaking.

So I took a towel I readjusted the clamp, and started to retighten it until the towl came back without being wet. I am so glad that i didn't have to check that head gasket or anything.

Thanks to everyone for the help, hope to see you at Texas 2K8!!!

Whasian

 

[jdub]

+1 All of the supra owners in Northern California with 7m's and the few 7m owners here in Houston are setting the torque between 85 and 90 ft/lbs.

Whasian

The above statement illustrates ignorance and the kind of "group think" that gets guys in trouble working on this motor. And you ignored the remaining discussion that followed Adam's initial statement...exactly what I was getting at when folk start making up specs as they go. It doesn't make a crap difference what "all the supra owners in NorCal and Houston" are doing if it's flat wrong.

Before you go spouting off torque values that basically you've pulled out of your arse, I suggest you read this:
http://www.arp-bolts.com/Tech/TechInstall.html

Over torquing ARP hardware IS NOT A GOOD IDEA...PERIOD!

You can do whatever you want to your motor, but to say an over torque is fine when it is specifically warned against is simply dumb.