SC-400 over heating Im at My wits end

[Just Crazy]

Hi to you all,

Ok to start the H2o pump is 2 years old the lower radiator hose and thermostat is a week old radiator has been flushed and new fluid put in.

The temp needle goes to the red on the highway or when in the city with the A/C on.

I can beat the snot out of the car if I have the heat on. the temp needle wont budge from normal temp.

I had the car to My garage and they were clueless (honest for not charging me though! )

I guess I'm looking for a picture of the heating/cooling system to be able to self diagnose. Can anyone help?

Thanks Jonathan

 

[turbosix]

overheating is usually:

air trapped in system
blocked passages
faulty cooling fans
blown headgasket

 

[Lextreme II]

Its possible that you have air trapped in your system like Turbosix stated.

 

[Toysrme]

For modified cars (and cars serviced by people that are not good).
Ignition timing is big. Cam timing falling behind that somewhere.

 

[Nick M]

Or the radiator is clogged on the outside with dirt.

 

[Peewee]

Is it actually even overheating? or is the guage just reading wrong?

 

[turbosix]

Or the radiator is clogged on the outside with dirt.

unless you go mudding, very unlikely.

Is it actually even overheating? or is the guage just reading wrong?

gauge reading wrong would be one of three things

1. air trapped in system near CTS giving false readings because air is not much of a conductor of heat compared to liquids

2. low coolant levels giving the same as above

3. faulty CTS

 

[Just Crazy]

to the firewall on the pass side of the car is a vaccumme switch and a diaphram wich controls the heated coolant to the heating core. I ran a number of speed trials with the diaphram open and closed.
This is the problem I figured out because I can make it over heat or keep it cool by removing the vaccume line the the diaphram.

The parts @ the dealer are aprox 350$ .....ouch I going to rmove them and use My (hopefully tuned) skills and see if they can be fixed!


thanks

I'll let you know how things fair.

 

[1uzvl]

are you saying it runs hot with the heater off and runs cooler with the heater open?If so youve got a prob elsewhere.The heater is only acting as a extension of your radiator,losing heat through the element itself.When was the last time the tank was taken off the rad and serviced,if every thing else checks out ok (t/stat,airlocks etc)get that done.

 

[Nick M]

unless you go mudding, very unlikely.

I don't think so. Over the years, a lot of garbage builds up.

 

[turbosix]

I don't think so. Over the years, a lot of garbage builds up.

i have a 20+ year old car and i put a new rad in it a few years ago (larger, alum, free) and it was nearly spotless dude... no garbage or mud or anything.

not really sure where you live where garbage flies up and clogs the radiator after somehow making it past two fans and an ac condenser......

 

[Just Crazy]

Can anyone teach Me how to check if My H2o pump is working properly?

IE which hose to check and how much pressure should be their?

The 2 parts mentioned earlier diden't stop the car from overheating.

No dirt cloging the fins in the radiator...

1uz the radiator has never been off the car I used a flush kit and ran about 12 gallons of water through it then refilled.


Still frustrated...!

 

[cribbj]

First, I'm a Supra owner, so I'm not an expert with Lexi cooling systems in particular, so take my comments with a grain, but having said that, here's a few more things to look for and try:

1. Possibly your thermostat is sticking shut. This could explain why the system cools better with the heater on. When it's running hot, see if you can "feel" flow in both the bottom hose and top hose to the radiator. Try to collapse them with your hand (and a glove protecting your hand!). If you can't "feel" flow, then my money is on the thermostat.

3. With only a 2 year old water pump, it's hard to believe it's at fault, unless the pH of your coolant is similar to hydrochloric acid, and it's eaten the impeller away.

4. Think back to when the car was not overheating, then try to remember what has changed since then (ie what have you messed with?)

HTH,

John

 

[Gazzasore]

Mine was overheating too
2 years ago
Radiator was 90% blocked
& only overheated every now & then
Didnt cost much to have it cleaned
been good as gold ever since

 

[Just Crazy]

It seems to be every now and then too, I can't duplicate the overheating like I could before.

Gazza, did you have the radiator flushed? or acid dipped (something like that)
I did a flush and ran many gallons through the system the refilled it... to no avail.

Earlier today the temp was 82 deg F and I drove for about an hour then parked (engine off) for a half hr 15 min later while driving the needle spikes close to the red.
I turn the A/C off and bring it home. halh hr latter I can't get it to overheat with the A/C on too.

#$^*^% frustrated

 

[1uzvl]

Fushing the rad wont work if it blocked quite hard.Get it out and down to a rad shop and get it service.if that checks out you can eliminate that.Ive serviced heaps of rads through the years that can be 90% blocked (internally)and the customer only has intermitant problems.

 

[Toysrme]

Barring looking in the cap & seeing. I've always used the easyest test for a radiator, after having changed so many due to people not changing the coolant.

It's quite simple.

Drain the radiator, take the fan off & pick the radiator up. If it weighs about 15lbs. It's fine. If the coolant has gelled. A 15-20lb radiator will weigh 40-60lbs.

 

[Gazzasore]

I had my tanks taken off & cleaned properly
& I think thy put on a new top tank
only about $200 au