Mkiii Cooling sys Q's - Toyota Nation Forum : Toyota Car and Truck Forums

jsbenami · 03-08-2005, 02:22 PM

I know this has probably been beaten with a stick already, but the 7MTE's do seem to run quite hot even for normal operation. I have turned my car off and felt the coolant boil slightly in the top rad hose. Now I always run it till the auxilliary fans shut off. They seem to run frequently. Is there any advantage to switching to the red slicion base coolant on the 7m? I have also seen one where the fan and clutch were replaced with an electric fan.
I am going to get mine flushed soon to get maximum cooling. The rad needs a change of fluid, the bottle is just disgusting.

One more question, I know you can have shops test for headgasket leak by testing the coolant for exhaust emissions. I was wondering if there are home kits you can buy to test for the presence of such emissions in the coolant. I want to start checking my coolant on regular basis so that as soon as the HG go's I can have it replaced, instead of damage slowly occuring such as I have head of before. Thanks!

Jonathan

***bgrieger*** · 03-08-2005, 05:02 PM

7M's don't run hotter than anything else. You just feel the heat as that big snail absorbs and releases it in the engine bay. If you're boiling coolant, you have more cooling issues.

Stay clear of the abnormal coolants. Ours was designed to run on the good old prestone type fluid (or Toyota red...basically the same stuff). Check the condition of your thermostat, the rad, water pump, lines, rad cap (big reason for boiling there) and the coolant itself. If you have poor old coolant, or badly mixed (you take a sample in the coolant tester?) you get poor cooling. Flush and fill is a regular maintenance item. If there is a weak spot in the system, it's usually the user. Test it all, replace and I'm going to guess your problem goes away.

In order to be able to test, head over to your local snap on dealer and get the kit. Expensive, but works. Also be preapred for false positives. Gasses slowly get in regardless of the seal of the gasket, and not keeping religious over coolant condition will generate them as well. Many a person gets a false positive and spends a crap load to fix it, only to find out it was alright anyhow.

Bob

Jeeves · 03-08-2005, 07:09 PM

Personally, to test for a BHG, I'd rather rely on a good ole compresison tester, or if you have it available to you, a leak down test. The Snap on was never reliable enough for me.

As for coolants, I ran Toyota Red for a while and never will I run it again. It leaked everywhere. Around hose clamps, out of hoses, around seals. Everything was red. It gave me no cooling gains, nor did it assist anywere else. Besides that, I've since done a good deal of research. To put it simply: "If it didn't come with red coolant, don't put red coolant in it."

If you want to make sure your cooling system is up to capacity. Give it a good flush, buy a performance radiator, make sure your stock fan clutch is operating perfectly, change out the thermostat, make sure the fan shroud is in good condition (more important than you'd guess) and top it off with good clean green coolant. So far, no electric fans have been able to match the flow of the stock fan. Simple fact.

jsbenami · 03-14-2005, 07:46 PM

I flush that ORIGINAL old coolant outta there professionally at a shop. The techs and I just kind of stared in amazment at the nasty brackish hue of the stock reddish (now purple-brown) coolant that the vaccum sucked out the car only has 57k but still, afer 13 years wow. We put in regular green antifreeze. I also got a new 13lbs cap for the radiator. However when the car is shut off, after the engine heats up because coolant is no longer circulating, it deos still boil very slightly inside the thermostat housing where the hose hooks up. I guess that is somewhat normal esp after turbo-ing if and if it deosn't get to cool all the way down. That thing will get hot. I always let the car run for a few minutes before shutting it off, and if I have time, till the two little aux fans shut off. A bigger performance radiator might be a nice thing once I get my high idle fixed and my valves adjusted. I also dropped 600 on new tires today. Much better ride now. I think those tires were original too. The rears were as bald as Captain Picard, the fronts were 2/3 treaded but dry rotten and cracking.

Jeeves · 03-15-2005, 02:05 PM

Quote:

I always let the car run for a few minutes before shutting it off, and if I have time, till the two little aux fans shut off.

If you've got a factory Supra Turbo they all had warning stickers on the drivers door to do this. It's called turbo timing and there are devices out there that you can install that do it automatically. They're fantastic.

jsbenami · 03-20-2005, 09:49 PM

New question, is it normal when I'm turbo'n around for my temp guage to rise up and then dip back down. I have noticed that it will average between 1/2 way up and 3/4. This morning I sustained boost for a while under moderate accel up to a nice speed and it came about 90% of the way to the red, then soon dropped back down to 1/2. There deos not appear to be any air bubbles or pockets trapped in the system. I was just wondering if this is normal or indicitive of a failing thermostat or water pump. Thanks.

***bgrieger*** · 03-20-2005, 10:34 PM

No. That is very bad. The needles are so heavily damped that we normally see no movement at all from roughly the half mark, or slightly under. Movement indicates a very significant change in temps.

Have the entire cooling system inspected, replace the rad cap and the thermostat since they're easy to get to and cheap, and see if this continues. I'm the last person to jump on the bandwagon for the dreaded BHG, as most symptoms are mistakenly and prematurely concluded as a BHG, but actually are just poor cooling system maintainence issues. Now, that said, if everything else is working, those are the symptoms I had when my gasket started to go south.

Bob

jsbenami · 03-21-2005, 12:13 PM

Well the system was serviced already.... flushed, and the cap replaced. I have watched the car with the new clean coolant in it for long periods of time and I see no bubbles or anything discolorated about the coolant when its running. The temp stays steady when it idles and sits in traffic except the two aux fans run almost all the time. This car despite only 57k mi is probably at the point in its life where a new thermostat and fan clutch may be necessary. If the HG is going....we'll know it sooner or later

albertmdh · 03-22-2005, 10:07 AM

my temp gauge ussually gets up to about 1/3 after about a minute, then doesnt move until i turn the thing off.

jsbenami · 03-25-2005, 03:27 AM

Ok its back with vengance. Assuming there are no bubbles on a leakdown test with a pressure tester hooked up to the radiator (so far nothing exhibits or points to BHG) and was wondering if Supra radiators are known to develop clogs or restrictions in the small tubings. I am wondering if some internal rust or corrosion became loosened and is impeding flow in the radiator. The car deos not overheat in traffic infact you can sit in it all day, it deos not overheat to the red at all, it just runs hot, and usually after a moderate or hard turbo run the needle comes up to right below red, and then falls right back down. It deos not matter if you keep moving or come to a stop it will go up then back down. If the pump was bad those symptoms would not run that course. So I'll do a thermostat since its quick and easy....the mean operating temp seems to be edging its way up slowly. I talk to a Toyota tech he said there might be air pockets from the flush, but I ran it with the cap off and didn't get any bubbles.

Jeeves · 03-25-2005, 11:07 AM

Quote:

Originally Posted by jsbenami

Ok its back with vengance. Assuming there are no bubbles on a leakdown test with a pressure tester hooked up to the radiator (so far nothing exhibits or points to BHG) and was wondering if Supra radiators are known to develop clogs or restrictions in the small tubings. I am wondering if some internal rust or corrosion became loosened and is impeding flow in the radiator. The car deos not overheat in traffic infact you can sit in it all day, it deos not overheat to the red at all, it just runs hot, and usually after a moderate or hard turbo run the needle comes up to right below red, and then falls right back down. It deos not matter if you keep moving or come to a stop it will go up then back down. If the pump was bad those symptoms would not run that course. So I'll do a thermostat since its quick and easy....the mean operating temp seems to be edging its way up slowly. I talk to a Toyota tech he said there might be air pockets from the flush, but I ran it with the cap off and didn't get any bubbles.

Sounds more and more like a BHG. Have you done a leakdown? You mentioned it, but you mentioned it in the same sentence as your radiator, so I'm not sure what you're talking about. Supra radiators are like most systems, yes, they can become clogged by this and that. Luckily to replace them isn't too expensive.

The problem you're going to run into is this. The 7M-GTE is an iron block, aluminum head motor. This means that when that iron block heats way up, the head does to, and the long alum. head LOVES to warp. This just promotes a BHG. Legend has it that even one run towards/into the red is enough to warp the head and bring on a serious BHG.

albertmdh · 03-25-2005, 11:50 AM

i havnt gone much about 5000 rpm, and now im even more scared to, thanks.

Jeeves · 03-25-2005, 12:47 PM

Quote:

usually after a moderate or hard turbo run the needle comes up to right below red, and then falls right back down

RPM doesn't have much to do with it. It's all about boost, timing and detonation.

albertmdh · 03-25-2005, 02:32 PM

i think he means the red on the temp gague.

Jeeves · 03-25-2005, 05:05 PM

I know that's what he's talking about. Read his previous post, he was talking about RPM. I was pointing out that the fact was that it still got WAY too hot, rpm didn't matter.