Overheating issue, searches suggest BHG but i'm not convinced!!!

poboy69 · 04-28-2009, 04:05 AM

So I just bought an 88 N/A from out of state with plans of a 2JZ swap sometime in the future. Im driving home and about 60 miles from the dealer I hear a buzzing noise comming from the dash on the passenger side. At that time I look at all of my gauges and hear a clunking sound. I look in my rearview and see something black and about the size of my fist fly out from underneath the car.

At that moment I didn't know if I had ran something over or if something had fallen off of the car, but I did notice that the coolant temp gauge started flickering like crazy. It wouldn't go past normal operationg temp, but it would go up to it and back down at random times, like a shorted wire or something. I pulled over, inspected the vehicle, and found nothing wrong. No fluid pissing anywhere, no leaks, and the car was running fine.

I got back on the road with the temp gauge still flickering and about 10 miles later the gauge started flickering toward the hotter side. Then just like that it spiked to red. I immediatly pulled the car into a rest area only to find that when I stopped, there was steam comming up from under the hood. I popped the hood and noticed the steam comming from the firewall/back of the engine.

I called the dealer and they suggested that it could be a blown heater core, but I never noticed steam comming up from under the dash or a wet PS floorboard!!!

We checked all of the hoses and found 1 small 4in "L" shaped hose to be torn. The hose was in the back of the engine and ran from the block to the head. 1 hr later we replaced the hose and started her up. she started right up and it took her about 5-7min to warm up. She was running fine and the only coolant that I could smell was the burnoff from the block. I closed the hood and got in. As soon as I started driving the temp gauge spiked all the way up in the red and I stopped. I popped the hood again and this time the steam looked like it was comming from the center of the engine, around the intake plenum!

After that the car would crank but not start. I left it at a gas station and drove 4 hours home with a friend. Today I called the dealer and to make a long story short the said that they would offer to pay and see what the problem is but not give me my money back. The mechanic that got to the vehicle said that it started right up with no problems. They have yet to find the issue.

So I don't get what the problem could be. There was never any signs of a blown head gasket! The exhaust never poured out white smoke!!! The car started right up after sitting for a day. it will idle all day long, but as soon as you start driving the temp gauge goes crazy!!!

Any help would be appreciated!!!

SideWinderGX · 04-28-2009, 05:11 AM

The best way to get a BHG out of the way is to do a block test. If it's negative, you know it is a coolant line somewhere.

There aren't any coolant lines near the intake manifold that I know of. The ones in the back of the head are annoying, and there's another smaller one underneath the power steering resorvoir as well.

Assuming it's not a BHG, or if it is and you plan on fixing it, replace ALL the coolant lines, double check your work, and don't worry about them for another 20 years

ddmcse · 04-28-2009, 11:21 AM

you can't trust that temp gauge , mine used to do the same thing (spike) an aftermarket electronic temp sensor proved the stock gauge was whacked ..

the temp gauge is just one small problem you have .
odds are it's a BHG . it would be helpful to figure out what went "clunking "

poboy69 · 04-28-2009, 12:45 PM

Quote:

Originally Posted by ddmcse

you can't trust that temp gauge , mine used to do the same thing (spike) an aftermarket electronic temp sensor proved the stock gauge was whacked ..

the temp gauge is just one small problem you have .
odds are it's a BHG . it would be helpful to figure out what went "clunking "

I know, but it's somewhere on I30 probobly flattened out!

The dealer that I bought the car from just changed the clutch fan and radiator fluid. Is it possible that there is air in the coolant lines?

ddmcse · 04-30-2009, 09:00 AM

odds increased

I'm convinced

IHateHacks · 04-30-2009, 02:05 PM

Quote:

Originally Posted by SideWinderGX

There aren't any coolant lines near the intake manifold that I know of

There are 2 coolant lines that run under the intake manifold. One comes from the throttle body and connects to the water bypass pipe. The other comes from the ISC valve and connects to the lower intake manifold's integral nipple.

Bill UK · 04-30-2009, 06:08 PM

Quote:

Originally Posted by IHateHacks

There are 2 coolant lines that run under the intake manifold. One comes from the throttle body and connects to the water bypass pipe. The other comes from the ISC valve and connects to the lower intake manifold's integral nipple.

As IHateHacks said.

ddmcse · 05-01-2009, 10:48 AM

coolant lines on the N/A ? don't remember

Bill UK · 05-01-2009, 05:38 PM

ddmcse is right you know, the 7M-GE throttle body doesn’t seem to have any coolant pipes connected to it unlike 7M-GTE.

04-28-2009, 04:05 AM	#1
poboy69 Intake Join Date: Apr 2009 Location: DF-DUB Posts: 36	Overheating issue, searches suggest BHG but i'm not convinced!!! So I just bought an 88 N/A from out of state with plans of a 2JZ swap sometime in the future. Im driving home and about 60 miles from the dealer I hear a buzzing noise comming from the dash on the passenger side. At that time I look at all of my gauges and hear a clunking sound. I look in my rearview and see something black and about the size of my fist fly out from underneath the car. At that moment I didn't know if I had ran something over or if something had fallen off of the car, but I did notice that the coolant temp gauge started flickering like crazy. It wouldn't go past normal operationg temp, but it would go up to it and back down at random times, like a shorted wire or something. I pulled over, inspected the vehicle, and found nothing wrong. No fluid pissing anywhere, no leaks, and the car was running fine. I got back on the road with the temp gauge still flickering and about 10 miles later the gauge started flickering toward the hotter side. Then just like that it spiked to red. I immediatly pulled the car into a rest area only to find that when I stopped, there was steam comming up from under the hood. I popped the hood and noticed the steam comming from the firewall/back of the engine. I called the dealer and they suggested that it could be a blown heater core, but I never noticed steam comming up from under the dash or a wet PS floorboard!!! We checked all of the hoses and found 1 small 4in "L" shaped hose to be torn. The hose was in the back of the engine and ran from the block to the head. 1 hr later we replaced the hose and started her up. she started right up and it took her about 5-7min to warm up. She was running fine and the only coolant that I could smell was the burnoff from the block. I closed the hood and got in. As soon as I started driving the temp gauge spiked all the way up in the red and I stopped. I popped the hood again and this time the steam looked like it was comming from the center of the engine, around the intake plenum! After that the car would crank but not start. I left it at a gas station and drove 4 hours home with a friend. Today I called the dealer and to make a long story short the said that they would offer to pay and see what the problem is but not give me my money back. The mechanic that got to the vehicle said that it started right up with no problems. They have yet to find the issue. So I don't get what the problem could be. There was never any signs of a blown head gasket! The exhaust never poured out white smoke!!! The car started right up after sitting for a day. it will idle all day long, but as soon as you start driving the temp gauge goes crazy!!! Any help would be appreciated!!!

04-28-2009, 05:11 AM	#2
SideWinderGX 3" Exhaust Join Date: Feb 2007 Location: Syracuse, NY Posts: 203	The best way to get a BHG out of the way is to do a block test. If it's negative, you know it is a coolant line somewhere. There aren't any coolant lines near the intake manifold that I know of. The ones in the back of the head are annoying, and there's another smaller one underneath the power steering resorvoir as well. Assuming it's not a BHG, or if it is and you plan on fixing it, replace ALL the coolant lines, double check your work, and don't worry about them for another 20 years __________________ my car: 1987 brownish Toyota Supra Turbo, automatic 7MGTE engine with ~100k miles on it.

04-28-2009, 11:21 AM	#3
ddmcse 500whp yet? Join Date: Jun 2005 Location: CT U.S.A. Posts: 966	you can't trust that temp gauge , mine used to do the same thing (spike) an aftermarket electronic temp sensor proved the stock gauge was whacked .. the temp gauge is just one small problem you have . odds are it's a BHG . it would be helpful to figure out what went "clunking " __________________ 300+ RW HP Dyno run, jdm,mod turbo,3"exh,electfan,greddyboost Blown HeadGasket info My Supra KiXGaS

04-30-2009, 09:00 AM	#5
ddmcse 500whp yet? Join Date: Jun 2005 Location: CT U.S.A. Posts: 966	odds increased I'm convinced __________________ 300+ RW HP Dyno run, jdm,mod turbo,3"exh,electfan,greddyboost Blown HeadGasket info My Supra KiXGaS

05-01-2009, 10:48 AM	#8
ddmcse 500whp yet? Join Date: Jun 2005 Location: CT U.S.A. Posts: 966	coolant lines on the N/A ? don't remember __________________ 300+ RW HP Dyno run, jdm,mod turbo,3"exh,electfan,greddyboost Blown HeadGasket info My Supra KiXGaS

05-01-2009, 05:38 PM	#9
Bill UK AEM EMS Join Date: Jul 2006 Location: UK Posts: 891	ddmcse is right you know, the 7M-GE throttle body doesn’t seem to have any coolant pipes connected to it unlike 7M-GTE.

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