Overheating issue...Maybe?

[ChrisR]

Here is what the car does. After a cold-start, about 5-6 minutes into driving, the temp guage needle will get up to about 5/6th up the gauge. It stays there for maybe a minute, then returns back to about 2/3rds up the guage. It seems to repeat this every once in a while when I'm driving. Sometimes when I stop the car when the needle is high, I open the hood, and I can kind of hear a noise like popcorn popping, as if it really needs to cool down or something?

I have just replaced the thermostat about a month ago, so it shouldn't be that, also replaced the radiator. But after a bit of driving, the tube going from the RAD into the engine block is VERY hot. I think that is everything. I hope my car doesn't overheat while I'm doing a track event on the 17th.

Any Ideas on what might be causing the overheating? Or maybe it is just a problem with the guage or the temp sender or?????

 

[yamahaSHO]

Is the fan coming on when it is supposed to? Does it cool down when you turn on the AC(turns on fan) ane while you are driving?

Sounds like you may have a faulty ECT?

A bad ECT will cause the motor to run rich. The computer thinks the motor is cooler than it really is and throws more fuel into the mix to warm the car up faster. You will have more black soot out of your tail pipes, not so good gas milage, and the fan will turn on VERY late.

<small>[ July 08, 2003, 03:18 PM: Message edited by: yamahaSHO ]</small>

 

[twr]

Replace the thermostat again - it is sticking closed. I've had a couple bad out of the box. The other thing that it could be is a radiator hose. They have been know to seperate and balloon up inside blocking flow.

<small>[ July 08, 2003, 03:23 PM: Message edited by: twr ]</small>

 

[yamahaSHO]

twr:
Replace the thermostat again - it is sticking closed. I've had a couple bad out of the box. The other thing that it could be is a radiator hose. They have been know to seperate and balloon up inside blocking flow.

Terry,

He said the hose is hot... sounds like coolant is moving through to me. shrug

 

[twr]

yamahaSHO:

twr:
Replace the thermostat again - it is sticking closed. I've had a couple bad out of the box. The other thing that it could be is a radiator hose. They have been know to seperate and balloon up inside blocking flow.

Terry,

He said the hose is hot... sounds like coolant is moving through to me. shrug

Jason,

The oscilating temp guage is telling me that the thermostat is sticking closed and/or open or that there is a heat effected blockage in the system.

 

[ChrisR]

I will replace the thermostat again. It is a pretty inexpensive part. Yes the fan is coming on (and usually staying on for that matter.) to try and cool things down a bit.

As far as the coolant moving through the hose, yes, it does, but shouldn't the stuff coming from the radiator into the engine be cool (in order to cool the engine) ?

 

[Jr's Sho]

The temperature switch for the gauge is only $2.99 from Autozone, if you haven't already replaced it, it wouldn't hurt to do it and get it over with. Maybe your lower radiator hose is collasping under pressure? My recent experience with a thermostat that stuck closed resulted in an immediate overheating condition. Hope I helped.

 

[SHOZ123]

I would think that the lower radiator hose would be hot but not as hot as the upper hose. maybe 120F max as a guess on a hot day? Too hot to hold.

 

[yamahaSHO]

Which way does the coolant flow on these motors... Sorry, I have not worked on my SHO since Thanksgiving and I don't have a Helm handy. I am forgeting stuff about the SHO frown

 

[AutoSHO]

yamahaSHO:
Which way does the coolant flow on these motors... Sorry, I have not worked on my SHO since Thanksgiving and I don't have a Helm handy. I am forgeting stuff about the SHO

Out the bottom passenger side of the radiator, into the water pump, through the block and the heads, and back to the thermostat. The upper radiator hose vents hot coolant after hte thermostat opens, and it runs back into the radiator.

 

[ChrisR]

Ah ha. Thanks for the explaination AutoSHO. I always thought it flowed the other way.

Anyone know the part number for the correct thermostat for my car?

 

[yamahaSHO]

AutoSHO:

yamahaSHO:
Which way does the coolant flow on these motors... Sorry, I have not worked on my SHO since Thanksgiving and I don't have a Helm handy. I am forgeting stuff about the SHO

Out the bottom passenger side of the radiator, into the water pump, through the block and the heads, and back to the thermostat. The upper radiator hose vents hot coolant after hte thermostat opens, and it runs back into the radiator.

Thanks Chris, thats exactly what I thought thumb

 

[Guy Newton]

You might have air in your system, when I replaced my TS I had to work the air out by squeezing the upper rad hose. The TS didnt have jiggle valves, I think that might of been an issue with the air not excaping?

 

[Slo-Sho]

The way I tried it was after flushing my coolant system, I left the cap off the bypass "T" fitting and then refilled. Seemed to get most, if not all of the air out. It's too bad our cars don't have a reverse flow cooling system, that'd really be sweet.

 

[ChrisR]

Well, I replaced the thermostat with a Stant Superstat 65869. Nothing changed, still seems to be overheating.

However, I did discover that there is some steam and a whistling noise coming from just under the throttle body, somewhere around the t-stat area. After shutting off the car, there is a bit of steam, and the noise coming from somewhere under there for about 20-30 seconds. I can't find where the leak might be coming from. shrug

 

[twr]

The system needs to be sealed to work properly. It's probably one of the coolant hoses from the TB and or IAB that is leaking. It's a pain to get to and you will need to remove the intake. I think autozone rents a coolant system pressure test, that will help in locating the leak when the car is cool.

<small>[ July 09, 2003, 04:11 PM: Message edited by: twr ]</small>

 

[AutoSHO]

For a quick fix (and to see if its the problem) you can bypass the manifold coolant lines and just loop the hose so that you eliminate the TB circuit.

 

[ChrisR]

AutoSHO:
For a quick fix (and to see if its the problem) you can bypass the manifold coolant lines and just loop the hose so that you eliminate the TB circuit.

Could you possibly explain how I would do this? I don't even know where to start... headbang

And now after driving the car today after replacing the t stat, the needle on my temp guage was at the very top line, at the "H" letter! I limped it home about 2 miles, and shut it off, steam pouring out. Although now that I think about it, it smelled more like burnt coolant? Maybe? But what do I know??? Maybe I will just have to take it into a shop and say fix it. doh

I just washed and waxed the car today so it looks great, but now it runs like **** rant cuss

<small>[ July 10, 2003, 02:35 AM: Message edited by: ChrisR ]</small>

 

[Jr's Sho]

The search function should reveal a lot of info on the TB/IAC bypass. I'll try my best to explain it without pics. If you lean over your drivers side fender towards the pass. side(directly in line with your TB intake), there will be a coolant hose that is on the firewall(right) side of the TB. Pull it off the TB and let it hang. Now there will be a coolant hose attached to the water outlet housing that is a little above and MAYBE a little to the right of the t-stat that will be hook to the IAC valve. What you want to do is pull the hose that it a little above the t-stat off of the water outlet housing and let it hang. Now the first hose which you pulled off the TB you want to connect to that water outlet housing port. Your just bypassing the flow of coolant through the IAC valve and TB. Removing the intake makes this a little easier and allows for you to remove all the hoses you are bypassing and it shows you more clearly exactly what you are doing. I hope I explained it good enough. Paul has a great write-up with pics somewhere.

 

[haydenm315]

SHOZ123:
I would think that the lower radiator hose would be hot but not as hot as the upper hose. maybe 120F max as a guess on a hot day? Too hot to hold.

I doubt 120F is too hot to hold. Temperatures out west are getting to 115F. That's not hot enough to cook you, but it's not comfortable. My sho tends to warm up on hot days. On a day where it was over 95F my temp gauge was constantly a little bit below the o in normal. Usually my car runs around m and a, however if it's hot and I'm stopped, it will get up to the top of the o. After getting up to the top of o, the fan will turn on and the needle will jump up a tad before going back down between o and r. I did a full flush of the radiator, heater core, and engine block when I did 60k. It seemed to help some. I think a new radiator is in store. There is a thread regarding a performance radiator group buy in the forums. I recommend checking that out.