Tell me if this is BS

[gtsfirefighter]

My buddy is looking for a supra. We found a nice 90 N/A that's real clean. Guy says he just spent $2600 to have HG replaced and a few other things. Admits he thinks the shop may have screwed him over.
Tells me the car has started to overheat and boil over. Also said one of the coolant hoses was sucked flat (???). He thought it was the thermostat. He removed the thermostat and it still overheated. He then lowered the price.
Well today he advised that a friend who is or was a "toyota mechanic" told him the problem is with the heater core and that is causing it to overheat. He admits there's coolant on the floor but the engine has plenty of coolant in it. So he goes back up on the price.

I have NEVER heard of this and neither has my mechanic, who works soley on Supras. Just looking for some opinions.

 

[CyFi6]

Don't buy a car that is overheating unless you are prepared to throw some major $ at it. Doesn't matter who claims what the problem is, until its fixed you don't know.

 

[wornoutsupra]

Kind of sounds like BS to me, and agreed^^^^^.

 

[suprarx7nut]

Hmm.... hose sucked flat and heater core problem dont really jive.

If the heater core has a significant leak, that would keep the coolant from pressurizing and easier to boil. That would explain the overheat, but not the hose suckled flat. :dunno:

Either way, it's obvious that thing will require some heavy work. If there's coolant on the floor, that certainly means the dash needs to come out.

 

[RogueCustoms]

I agree with everyone above. Don't buy it... There's going to be a lot more money going into that car. And, any respectable car owner would fix the problem before selling or drop the price considerably since the future owner will have to fix it.

Just my thoughts.

 

[gtsfirefighter]

The intention was to buy it and do a stock rebuild on the engine. My bud doesn't want crazy power and a GE will suit him just fine. I know the amount of work that's going to be involved and it will be extensive. I've pulled a few engines in my time.

I just want someone to explain to me how a heater core would cause an engine to overheat, especially if there is plenty of coolant in the system to circulate. I say there is no explanation.

The car is question.

 

[Suprapowaz!(2)]

I'd offer him $800 for a car with serious problems. Don't buy it, walk away, find another MKIII.

 

[gtsfirefighter]

Appreciate the comments but I'm not asking if I should buy it.

Before I talk to this guys mechanic I want cold hard facts to prove he don't know what he's talking about.


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[Backlash2032]

The only way I can think of is if its leaking there would be a pressure drop in the system, so the coolant would boil more easily.

 

[Supracentral]

Here's something I posted a long time ago (see bolded text below) when talking about BHG's on the 7M that may apply here:

Tests have shown that as little as 0.04% (400 PPM) water in lubricating oil can cut the fatigue life of bearings by as much as 48%.

Moisture is generally referred to as a chemical contaminant when suspended in lubricating oils. Its destructive effects in bearing applications can reach or exceed that of particle contamination, depending on various conditions.

Water may cling to metal surfaces or even form a thin film around solid contaminants such as silica particles. But by far the most damage is done when 'etching' occurs.

Water etching is a common type of corrosion occurring on bearing surfaces and their raceways. This corrosion is caused primarily by the generation of hydrogen sulfide and sulfuric acid from water-induced lubricant degradation. Yes, you read that right water (and anti-freeze) when mixed with oil and heated inside an engine combine to form acid. This eats away the soft surfaces of your bearings in no time.

(Ever notice that a Supra with a BHG for any length of time will have rust in the coolant? - Guess what - the coolant has become acidic by mixing with the exhaust gasses that are getting into the water jacket!)

Remember your bearings are never supposed to "touch" anything but oil. The bearings ride on a very thin layer of oil. Once there is some etching, the oil pressure drops (since the etching has provided the oil with a place to go other than where it is supposed to be) and eventually the bearing touches the rotating surface. After that it's all over.

The absolute most common failure mode of the 7M head gasket is to get compression into the water jacket. When they fail like this they tend to run fine and push coolant out of the overflow bottle all the time.

Acidic coolant will eat the living shit out of a heater core and could cause the aforementioned coolant on the floor.

Also, any aluminum head that has been subjected to overheating needs to be checked for hardness. If the head is down to 65 Brinell, it's garbage.

 

[gtsfirefighter]

We might go look at this car tomorrow. If we do I'm going to bypass the heater core and do a leakdown test to prove its not what he was told by his mechanic friend.


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[Poodles]

Block test that tests for exhaust gasses in the coolant would be a dead give away.

Sucked flat hose can be a number of things (blocked t-stat, bad radiator cap, other blockage in the system).

 

[te72]

Flat hose tells me you have a vacuum of some sort in the system, that's the only time I've ever seen a flat hose, is when a buddy of mine was helping me fill the Mk2 with fresh coolant after the rad swap. Had a neat tool that uses compressed air to suck the air out of the system from the radiator cap, puts a hose in a bucket full of fresh coolant, flip a switch, and voila, no need to burp. Interesting side effect, said tool created a complete vacuum in the coolant system, so all the hoses got sucked flat as could be.

Like Poodles said, it's likely a blockage, and my main suspect would be that the water pump is generating a vacuum.

All that said, if the car is clean otherwise, and a nice shell... I'd say it's still worth considering. GE's aren't terribly expensive.

 

[RazoE]

You can pick up cheap 7MGE's for a few hundred, buy a spare, do a HG job and drop it in..

 

[gtsfirefighter]

I spoke to his mechanic friend today and they both listened to reason and the owner came back down on the price. Now the problem is my bud thought he had the money together. Wrong.

We're done here.

 

[Poodles]

Slap your bud

 

[FernandoDLT]

Was this car located in denton???

Fernando

 

[Nick M]

I just want someone to explain to me how a heater core would cause an engine to overheat, especially if there is plenty of coolant in the system to circulate. I say there is no explanation.

The car is question.

Because it is leaking. A collapsed hose is becuase of depressurizing of the system. The opposite of what the cap does. To check what Mike mentioned, go to Napa buy a block tester and ask him if you can test it. When it turns color, you know there is bypass into the cooling system. Nice shell. I would take it, for a low price because of the rebuild needed. If needed I should say.

 

[gtsfirefighter]

Well an update. My buddy bought the car and I drove home the 180 miles it took and never had one issue. We truly believe that the overheating issue (in stop and go traffic only he said, not highway) was due to the fact the he did not have enough coolant in the system. We added a lot of coolant to it before we left. The overflow was almost dry as well. Since he bought it, it has only used coolant due to a bad hose and leaking drain on the radiator which we have taken care of. The 7M sound like a sewing machine but overall runs really well. A stock 1JZ swap is the plan. We are going to sort out a couple of suspension issues and some other little things first then he'll save for the swap. It's a pretty decent car.

 

[suprahero]

If I ever need anyone to go look at a car, drive said car back home for me...........you're hired!!!!