5me overheating

[varment]

Hi everyone, i have just rebuilt the head on my 5me in my ms112 coupe but now i have a overheating problem, not sure of previous history but the original owner said it had an over heating issue that caused the head gasket too go, but upon pulling off the head i noticed it had majorly corroded holes from the water jacket into the valve seats, so i guessed that was the heating issue so i sourced an reconditioned a another head and reassembled.
it has a new clutch fan,water pump and reconditioned radiator.
the problem im having is that under normal driving it runs half temp on the guage this is fine untill i put it under load like putting the foot into it and as soon as i do that she rockets up to boil point and wont come back down.
Hoping this sounds familiar to somebody any suggestions would grateful

[supra2]

Is it useing water or pushing out?
Did you bleed the system with the heater tap on?
Has the water level droped when you recheck the rad when cold?

[Dan_k36]

Radiator cap and thermostat have they been replaced as well?

[varment]

i have a new thermostat and rad cap

i havnt opened heater tap to flush would that cause overheating though?

it dosnt use water only pushing it out when it comes to boil, trying not to let it get that hot

i have also started with top hose off and thermostat out to make sure water pump is not faulty and its fine and have also ran without thermostat and it will still come up to temp under load just the same, some one suggested that the bottom hoses sometimes flatten and suck tight under load could that be possisble

[4th surf]

OK possible causes and one you've admitted..

Airlock or blockage in the heater core.

Restricted or blocked radiator core, did you have the radiator serviced when you did the head? A blockage or restriction can cause hoses to suck in.

As you've ruled out the fan clutch by replacing it. Do you have the correct coolant in there? Toyotas seem to really dislike the green stuff but behave well with the red stuff (I won't explain unless asked but every toyota I've ever had in that died as a result of overheating seems to have green coolant in but never had an issue with the red stuff).

I'd also assume that the car is automatic being MS112. if so what condition is the trans fluid in? Nice and red or a burnt brown colour smelling like burnt toast? External trans cooler fitted?

Does it have A/C? If so is the core of the condensor not full of crud as to not restrict air flow?

Check your brakes? Are they binding esp when at operating temp.

Is it using coolant? Given that you have described a rotten cooling system checking the core plugs for leaks might be a go too

[supra2]

One thing I did to my 3tgte while it was apart was remove the welch plugs and clean and scrape the settled corrosion in the bottom of the water jackets.
I was amazed as there was close to 20mm sitting in the bottom of this old engine reduceing its cooling around the cylinders.
Now, even during the hottest rallys, its doesnt raise a sweat.

You said your old head was badly corroded. It may be the block is full of rust as well.

[Dan_k36]

Why don't you by pass the heater and see if it still over heats?
Have you replaced the temp sender? Coluld be broken inside the sender its self ?

[crownv8]

Sounds like radiator to me. I bought a MX73 (5me) with a supposed reconditioned radiator and it did the same thing from day one. Was fine most of the time but as soon as you put load on it the temperature would go up. I did all the things you have done then finally took the radiator to out and the guy said it was 50% blocked. Once it was done and back in the car was good as gold.

[varment]

ok so far i can rule out radiator as i had it serviced and was 30% blocked but nothing changed.

as for heater tap i pulled it off tonight and it was jammed shut with crud so it would not open i cleaned and loosened it up and put back on, while doing this i noticed the vacume hose from tap to the climate control box was dodgy so i will replace then this led me to open up the climate control box to reveal the little solonoids and hoses which are all broken off so i dont think the heater tap had any chance of opening i wil replace them aswell and see what happens,


if this dosnt work i might try bypass heater and see what happens

thanks people this feedback is very helpful i just hope its not the block that is blocked up as i didnt recon the bottom end i just cleaned and blew out best i could.

[allencr]

Gauge? 'rockets up to the boil point' isn't a engine or cooling system problem if it is happening that fast.
Also. Look in the radiator to see if it is blocked up. Being reco'd doesn't mean that stuff stuff from the block when it dried out hasn't come loose & blocked it again.

[varment]

cheers allencr i think this might be 1 part of the problem as it looks to be scummy in there again is there anything i can add to cooling system to break down the crap that might still be in the block.
now that i free'd up the heater tap its leaking from the little vacume plunger grrr
so there is a couple of issues it seems

[allencr]

'scummy'?
So what, lots of automotive & house cleaning products near by can make it look nicer & little else. What can you see that's possibly blocking the core's tubes?? More then 1/4 clogged? Can you see thru the cap, and how clean are they. When being drained, they should go down at the same speed.
Scum, film doesn't conduct as well, but usually collects in the high spot and won't hurt anything but looks & a little volume. Don't dump anything in there if you don't know what you're cleaning - scum, mineral buildup or mechanical blockage of the core tubes with bits of rubber, mud/corrosion/flakes/smegma, silicone/gasket cement.

[varment]

today i gave the rad a real good flush, flushing alot of crap out like corrosion scale its like grit.
after a good flush i refilled and took for a spin its much better but not fixed so i think will keep flushing the system a few more times then get the rad serviced again and replace the heater tap

[crownv8]

Maybe talk to your radiator guy about doing a power flush before you pull the radiator out again. If there is still stuff floating around you may just block the radiator again. There are chemical flushing agents you can buy from repco etc. I have had reasonable success using these.

Just follow the instructions to the letter though. That's right. Read the instructions before you use it not after. ;-) Not an easy thing for us guys to do.

[alexlegault]

have you checket your thermostat