Overheating 4k

[greenmac80]

ok so my daily got a 4k in it.

 

when i did the swap i put a new rad cap and thermostat in it.

 

the water pump... according to tally was reasonably new.

 

didn't have any problems for a few weeks.

then one morning i'm cruising to work and the temp gets to 3/4's

i pull over thinking wtf?

 

check uner the engine bay to find the overflow was all good so again i was like wtf?

 

anyways headed to work and i didn't get hot again.

 

talked to mate and we checked my rad cap.

 

turns out it was the wrong one 7psi and no jiggle valve so even tho the overflow was full the rad was half empty.

so i got a 13psi rad cap with a jiggle valve.

 

still nothing changed.

 

this is the scenario.... on start up i drive. cruise down sth rd it starts getting really hot.

i drop back a gear rev it out a bit and then return to normal cruising. temp drops!?? wtf?

and from then i have no problems whatsoever.

 

now this was suggested to me. water pump might be cavitating?

now this may be possible but the pump is reasonably new.

 

has anyone else had this problem or something similar? experiences etc?

 

cheers, Luc

[Evan G]

dodgy tempgauge?

 

was there steam pouring out the overflow?

[greenmac80]

nah no steam jst hot boiling fluid. so yeah i guess steam. but not much temp guage works fine you'd think it would always read wrong but like i said

once i've revved it it returns to normal.

 

i suppose i can test the guage.

[Evan G]

$50 from autobarn gets you a autotechnica digital temp gauge.

[greenmac80]

nah i have a speco one i can put in. but still i don't believe its the problem.

[Raven]

Did you bleed the cooling system to remove any air pockets?

 

Tried swapping over the temp sensor for a known one that works (old motor perhaps)?

 

Blocked radiator may also be an issue. Reverse flush it and see how you go.

[greenmac80]

hmmm i would've thought that the cooling system would bleed itself using the jiggle valve in the radiator cap.

i could be wrong but i reckon i'll try that first.

 

the sensor came off the 3k that was originally in the car. well the whole housing was this is why i don't believe that'd be it as it worked fine the entire time i've had it.

[Raven]

I'll never trust those jiggle valves. Ever.

 

Fill her up and let her idle until everything starts expanding and overflowing.

 

Squeeze the top hose to get any air out while its expanding and top it up.

 

The only other thing could actually be a dodgy impeller on the water pump, which is a possibility.

[greenmac80]

hmm well now after a long drive it overheated badly

might be fubared won't know till it cools down

[jason12]

If its ok drain your coolant / water or whatever out then get a 2L coke bottle and cut it in half and electrical tape the bit you drink from until it fits in the rad and doesnt let air in, now completely fill the rad thru the coke bottle. This will make sure theres no air etc in the system. Would be a start at least

[greenmac80]

well there was a lot of steam coming from the back of the head.

so i'm gathering that the rear heater hose may have a hole in it.

 

only thing is i've never noticed it leaking the car doesn't leak fluids at all.

so meh

i'm gonna fill it up in the morning get to work.

drive home to the workshop replace that rear hose

and dump the coolant and start again with that bleeding the system etc.

if that doesn't fix the problem then i'll change the water pump.

 

i'm getting soo sick of k motor and everything related i tell you.

 

4efe couldn't get in there quick enough. mmm new stuff.!

[greenmac80]

I'll never trust those jiggle valves. Ever.

 

Fill her up and let her idle until everything starts expanding and overflowing.

 

Squeeze the top hose to get any air out while its expanding and top it up.

 

The only other thing could actually be a dodgy impeller on the water pump, which is a possibility.

 

 

dodgy impeller? please explain dodgy how?

[RainWarriorDregs]

clogged up and seized?

[SLO-030]

Cavitated and thrown the clearances out beyond limit. Reducing the efficiency of the impeller.

 

Explain why it gets warm, then gets the water moving quicker when it gets revved, hence the cooling down.

[Evan G]

dodgy impeller? please explain dodgy how?

 

if the fins on the impeller have corroded off, its not going to 'pump' coolant around the engine therefore cook

 

 

the customer came in with a cracked timing cover, we had to remove the waterpump witch we discovered this! LOL!

Edited May 16, 2010 by Evan G