VS V8 overheating with new radiator

[crumpledoor#1]

Bought and installed brand new radiator for my vs v8. overheats within first 10 mins of driving. I ran the heater when filling and it was fine. Now when go for a small drive of 10 mins the bloody thing cooks. I run LPG but this should make it run cooler. Could my water pump or thermostat be stuffed? How can I tell if the water pump is shot? Help please!!!

[Proman]

not sure but probably change theremostat check all sensors etc, does the cooling fan come on at all?

[Azza SS]

if you can get your thermostat out quickly throw it in a bowl of boiling water and see if it retracts, or Drive the car without it just for testing. Sometimes there is a bit of muck on the center shaft and it wont move freely. Was the Car cooling o.k. before you changed radiator? perhaps not as to the point of buying a new one.

[SUSS8]

Try the thermostat first, its easier to work out. Take it out and put it in a cup or bowl and poor some boiling hot water in it and it should pop open. If not well then its no good. If you get yourself a new one ask for one that opens at about 77 degrees celcius. I had the same problem less than a week ago. OH and before you put the new thermostat in test it first the same way!!!!!

[T-rex]

One thing is are you sure its a v8 radiator? Because if its not, a 6 radiator shouldn't have the capacity and thats why it would do it after 10 mins of driving.

[Vee-ard]

Its not bled properly, you've got air in the system if its overheating after a new radiator. You need to run the engine at idle with the heater turned on to max until the car reaches operating temp. bleeding the air at the same time obviously.

[crumpledoor#1]

It's been bled properly, I replaced the clutch fan with a 16" thermo fan which kicks in no problem. Only problem is it keeps running because the car gets too hot. With it running constantly it keeps perfect temp but I suspect this will kill the new fan in no time. I checked the thermostat which opens without issue. Water pump is pumping, I know this because with the radiator cap off I rev the car and the coolant level goes down. I am totally stumped! Heads and head gaskets are fine also. Seeing as the the fan stays on then I also suspect that the sensors are fine and the gauge shows a proper reading. I just can't work this one out!

[crumpledoor#1]

Oh and yes, it's definately a v8 radiator.

[VS_Pete_1]

Mate I bleed my v6 for two or three days till all air is out and run heater fully open.
fill bleed
go for drive bleed cheak for leaks
go to work bleed
go home bleed
go to work bleed
after 2-3 days no more air.
give it another bleed just in case

[crumpledoor#1]

V6 is diff to v8. V6 has a bleed screw but v8 doesn't. Not that ive found. I don't think it's a bleed issue but then again I'm so frustrated that I will try it. Still open to any other ideas??? Would it run hotter if the gas needs tuning?

[hako]

First thing to do is check hot coolant is actually flowing through the radiator core - do this by checking that air being blown by thermo fan is hot - if it's only worm or cold then the radiator core is either partially or fully blocked. If it is blowing hot air then I'd lay London to a brick that you've got a blown head gasket or worse.

[seq4x4]

I thought LPG ran hotter then petrol?

[crumpledoor#1]

First thing to do is check hot coolant is actually flowing through the radiator core - do this by checking that air being blown by thermo fan is hot - if it's only worm or cold then the radiator core is either partially or fully blocked. If it is blowing hot air then I'd lay London to a brick that you've got a blown head gasket or worse.

It does blow hot air, hot as fark air. The head gaskets blown would either show signs by water in the oil or blowing clouds of white smoke wouldn't it? Neither of which I have.

[db_notso]

so you replaced the fan.... just a thought is it blowing the right way? (is it blowing with the air direction from the front of the car towards the back? regardless of where you installed it)
sounds stupid but ive seen it before, would overheat when driving not when just idling there but.

[crumpledoor#1]

so you replaced the fan.... just a thought is it blowing the right way? (is it blowing with the air direction from the front of the car towards the back? regardless of where you installed it)
sounds stupid but ive seen it before, would overheat when driving not when just idling there but.

Yes it's blowing the right way. I made that mistake when I first dropped it in but realized quickly and reversed the polarity. So whilst it sounds stupid, I did do that at first but this was prior to a test drive. Still stumped! Short of striping the top of the motor and changing head gaskets I dunno what else to do.

[crumpledoor#1]

so you replaced the fan.... just a thought is it blowing the right way? (is it blowing with the air direction from the front of the car towards the back? regardless of where you installed it)
sounds stupid but ive seen it before, would overheat when driving not when just idling there but.

Yes it's blowing the right way. I made that mistake when I first dropped it in but realized quickly and reversed the polarity. So whilst it sounds stupid, I did do that at first but this was prior to a test drive. Still stumped! Short of striping the top of the motor and changing head gaskets I dunno what else to do.

[db_notso]

okay then next up you could check some things yourself cheaply

take your radiator cap off and let the car run (with heater on a/c off) until fan comes on if you get little bubbles coming up in the radiator a pretty good sign its a blown head gasket (leaking compression HOT into your coolant)
this process is also the easiest way to bleed these puppies anyway as you can keep topping it up as it sucks the water into it.

after this thermostat pull it out put a coathanger throught it and drop it into boiling water and see if it opens up if not answer is thermostat

the easiest way to check if a water pump is working is to pull a heater hose off with engine off and hold your finger over it then start the car you should feel a preassure difference
this is not exactly the "correct" way to check it though, your supposed to remove and inspect it.... but anyway!~
but pumps are noisy if die at low kilometers and at high kilometers they disintergrate (RUST AWAY) you wont feel like a high pressure but will definately be differnt TO ENGINE STOPPED off get it?

[crumpledoor#1]

Cheers DB. I had small bubbles coming up when I was bleeding the system but I thought these were just air bubbles coming out of the system. They were very few and far between and very small air bubbles. Would there be any other signs if it was a head gasket? I don't have water in oil or blow white smoke.

[hako]

I'll still bet London to a brick it's a blown head gasket - why did you put a new radiator in?.......was it overheating previously?

[db_notso]

now there will be some bubbles if it isnt bled properly FYI !!!!
make sure you bleed the crap out of it before you go stripping it down!!! the correct way with the screw yeah???


and when hot running cap off
rev it whiile looking into radiator at cap if blown head this way there will be a large amount of air coming out
if it is blown this way you may need to have heads machined aswell as gaskets....

but i would get it hot and do a compression check on EVERY cylinder first to confirm head gasket leaking coimpression

[VR38]

I would say if you had no problems till you replaced the fan then either the new fan is not up to the job or after reversing the polarity the fan blade also needed reversing as some are only designed to pull air one way.

[crumpledoor#1]

I just bought the car about 4 weeks ago, the radiator leaked from corroded cores and when I pulled it out half was blocked with leaves and crap, the other half from leaking trans oil and dirt from the trans cooler. It wasn't over heating but the temp was very erratic. So I replaced it plus got rid of the clutch fan for the thermo fan. So it wasn't over heating but it never ran at proper operating temperature. I'm starting to think it must be a head gasket. I'll do a compression check tomorrow and also do the cap/bubble check again. I have never owned a v8 before or a car on LPG. It's a bit of a bitch to start but I thought that was the gas needing a tune but maybe that's another sign of the head gasket being stuffed. Idle can be smooth 98% of the time but every now and then it gets a bit rough. I guess the good thing is, I have rebuilt engines before (only straight 6s) so I should be ok to do this job, all be it a big one.

[crumpledoor#1]

Fan functions fine and the blades are the right way and polarity is also the right way. 100% to manufacturers instructions.

[db_notso]

hard to start aswelll you could before you did the compression check pull plugs out and crank the car over if water squirts out thats a really sure sign of head gasket.

[crumpledoor#1]

Dam dam Dam!! I was hoping it wasn't going to be but it sounds head gaskety.
Water shooting out??!! Might have to get my son to come and see the giant water pistol daddy drives lol......gotta laugh, if I don't I will cry!