Help w/ overheat condition ?

[jgscott]

I need help. I have a 97 SC400. I pulled my stock motor to do a complete perfromce engine build up.

The problem I am having is with a different used 97 SC400 1UZFE motor that I bought used, and, installed while I build my original motor.

The used motor had 101k miles on it and was from a wrecked car. I checked the service history and it was serviced good. I installed it and used my existing ECU which plugged up fine.
The motor runs hot as indicated by the in dash temp guage. After 5 mins of idleing the dash temp guage shows the needle peaked way past the H ( hot), The motor then starts to skip and miss and throws a CEL. The CEL read Misfire on just about all clyinder, Bankl 1, and says too rich. Here's what I have checked, and done so far.

- Re bled and flushed the coolant system for air about 3-4 times.
- Changed the thermosat & ran with no thermostat.
- Changed the top mounted, front temp sending unit.
- Checked the fan, and flushed the fluid in the fan pump system.

Today we took a independant digital temp guage sending unit, and put it in the coolant at the sending unit openning, and bleed valve openning. The bleed valve coolant temp was about 160 degrees, and the temp sensor opening coolant read 170 degrees. Someone told me the thermostat was set to open at 210 degrees, so even tho it shows hot, I don't think it is really that hot as the dash indicator says.
The car will throw a CEL light and the start running like crap when it starts showing a reading in the dash temp of above H ( hot ).

I thought about if that used motor could have a blown head gasket, but if that was causing it to go hot. I would think that the coolant temp reading I took would show temps way above 170 degrees and I saw no evidence of water on the dipstick.
One other strange thing is that when I pull the oil dipstick when I shut the car off after it shows HOT, I hear a hiss of pressure release from the dipstick tube.
Anybody know what it could be ? Is there a second sensor that could be bad that is fooling the dash tempature reading and then thus fooling the ECU and confusing it to think that it was HOt ? Thanks.

 

[Lextreme II]

Scott,

Sorry to hear your trouble. Do have any status on the water pump? Any water leak infront of the engine during hot engine and engine shut off? There are few possibilities your car might be hot:

1. Water pump
2. Thermostat
3. Radiator
4. Fan
5. Possible internal engine problems.

 

[cowboy bebop]

Agreed, check you water pump first to ensure that coolant is actually flowing. Run teh car from cold with the radiator cap off, and check for proper flow. You should see a mighty current in there.

If that checks out, fill the coolant level to the top, and start the car (cap on). LEt it get hot, and near overheat, then shut it off. Let it cool for a few hours, and recheck your coolant levels.

If your coolant levels are low, then you have to be leaking either from an internal or external source. Check your heater hoses for and coolant residue, as well as any coolant ports on the motor. Check your radiator hoses, the radiator itself, and under the car for leaks. If that checks out, pull your plugs and smell them for coolant. If you're burning coolant, you'll be able to smell it easily. Next, check closely your oil cap, and your dip stick. If they are ilky in any way, then you have coolant leaking into the oil system, more than likely through the head gaskets.

The coolant system is a PITA, but it's only got a couple places that it a problem can be.

Eric

 

[jibby]

You can always intall some electric fans for a few hundred dollars which I just did on my sc.. It freed up room and made a little hp. Something to think about if you still can't get it right...electric fans will also run independant from the cars ECU and sensors and will bolt right onto your existing radiator.. that is if the water pump isn't the answer to your problems...

 

[Kiwi.in.aus]

Jibby you are missing the point , they don't run hot standard , so why is his ?
Just a thought , check that the timing is right , maybe something is amiss with that engine and your ECU ?
If your timing has been advanced for some reason it will run hotter .

 

[jgscott]

Yeah I did change and put a New Lexus water pump on it. I was kinda thinking about that today. Would have to be a bad new factory part.
My 97 Radiator does not have a cap, so the fill is in the overflow res. I don't think you can see the fluid flowing.
I got fed up today and took it to the Lexus dealer. They said they would check it Monday. They think it might be a pinch or short in the wire harness. I had no leaks that I could tell at all.

 

[jgscott]

Jibby you are missing the point , they don't run hot standard , so why is his ?
Just a thought , check that the timing is right , maybe something is amiss with that engine and your ECU ?
If your timing has been advanced for some reason it will run hotter .

If the timming was off, would that let it peg the temp needle past H ? Just at idle ?

 

[jibby]

Kiwi.in.aus- I don't think I am missing the point at all.. This car is overheating... jgscott the owner changed the thermostate, flushed the radiator, checked that the that fan is working properly, and was then going to check the waterpump. That almost covers the complete cooling system. So then I would assume maybe there could be a coolant/water flow blockage in or near the engine block which is unlikely causing the car to overheat regardless. Could also and most likely be in the wiring/ECU/sensors or something to that effect would be my next guess..

In regards to your suggesting that it could be the timing, the engine runs fine and then overheats so somehow I don't think the problem is with the timing my friend. I think I understand the problem completely do you?

 

[Kiwi.in.aus]

My point was Jibby that he needs to get it running correctly standard before he worries about aftermarket fans and stuff .
A lot of the time these kinds of problems are more than one single thing , a series of faults , thats why problems like this are hard to fix .
Scott , probably not all on it's own , the timing would have to be a long way out to be the single cause , but seeing as he is running a different motor to ECU it is worth a check .
Jibby if you read my statement carefully I stated that if the timing is advanced it will run hotter and this is true . :veryhappy
I did say that he needs to check , easy to do and one more thing that has been eliminated , no where did I suggest that this is the single cause of his problem ?
Normally these things are solved by a process of elimination " If you eliminate the impossible , whatever remains however unlikely must be the solution "
Settle down old son !!
Your replys seem to come across a bit harsh ?
It's probably just the way you post and I wouldn't take offence , but some people do .
I miss points all the time , especially when conversing with my wife so please don't take it personally , it was meant with no malice .
This site is no different to any others , if you can't take a bit of banter meant with no malice even if it's wrong , then maybe one shouldn't post at all ?

 

[jibby]

Kiwi - I did take a poke back at you in response to your prior post that referred to me as being lost without a clue..:hitwithro (missing the point) I just took a jab back at you but it wasn't a right hook. All apologies...I have no problems with ya kiwi. :kiss:

My suggesting the electric fan was said because, first off - he's doing an engine swap and the fans frees up space and simplifies matters alot. Second, the electric fans eliminates a good portion of what could have been the problem with his cooling system.... anyway that is it, See yauttahere

These faces are funny on the "more" selection...

 

[jgscott]

Kiwi and Jibby, can you guy's take this to PM's please. Thanks.

 

[Kiwi.in.aus]

Sorry Scott , didn't mean to hijack the thread , I should have just let it go , life's too short and so on ....

No need to go to a moderator , we are both bigger than that !!
Please let us all know when you find the solution .

 

[jibby]

Jgscott - Just having a little fun, pm's were in order....what was I thinking:argue: . Don't worry we love you too:smlove2: ...

Ok enough clowning around, see ya-