overheating

[thezig]

Hi guys. I am a girl Patrol owner with minimal skills but willing to learn! I have a GQ 4.2 diesel, 92 model that has been the gutsiest car for ages. I am experiencing overheating. She always runs hot in summer but waaay too hot now. First thing was removing thermostat which helped. Next was replacing expansion tank which stopped the water loss. Also had a radiator flush. The viscous fan sounds like it's coming on. Have put on a new radiator cap and crimped up a heater hose. STILL TOO HOT! Especially under load, although the temp does come down somewhat in cooler ambience. There is no oil in the water or water in the oil. Is there something else I can do or am I looking at a new head?

[YNOT]

Welcome to the forum, what part of the world are you from? When you get a chance drop by the introductions htread and tell us a bit about yourself and your Patrol.

The first thing you need to do is fit a new thermostat, it's not good to run without a thermostat.
Check the A/C condensor for debris in the fins.
Make sure the radiator is sealed around the sides and bottom so all the air entering the front of the car is forced through the radiator.
When you say the radiator has been flushed, was that just replacing the coolant or take to a radiator shop to have the tanks removed and the core "rodded"? Unless the radiator has been rodded (a proper internal clean) it may still be the cause of the problem.You also need to check the radiator fins, if the radiator is too old the fins may be falling out. See the photo below.

http://i758.photobucket.com/albums/xx224/tonyh01/P1020064.jpg

If the radiator does need to be replaced look into getting an upgraded radiator.

Check the water pump for leaks, corrosion-especially under the hose (check the thermostat housing for corrosion under the hose as well), and worn bearings. To check the bearings hold one fan blade on either side of the fan and try to lif firmly up and down. There should be no movement.

How long has it been since the radiator and heater hoses were replaced? For reliabillity it may be time to replace them. Hoses fail from the inside out, so they may look OK externally but be close to failing. If you do replace hoses, remember to recheck hose clamp tension/tightness after a few days of driving. As the hoses settle the clamps will need retensioning.

When you refill the cooling system make sure the system is bled properly to get all the air out of the system. Park the car nose up so the radiator is the highest part of the system. Turn the heater to hot and let the engine idle (or up to 1500rpm) until the thermstat opens and coolant starts to circulate through the system.

In normal driving (ie. not towing) your cooling system should have no trouble keeping the engine cool in summer.
I would not suspect a head or head gasket yet.

Tony

[Woof]

Hi Thezig, its always good to post up an intro before asking questions, just to get everyone on side.

[thezig]

Hi Thezig, its always good to post up an intro before asking questions, just to get everyone on side.

Sorry about that - I thought i had but tech skills must've failed me! I think i'm up and running now...

[thezig]

Hi Thezig, its always good to post up an intro before asking questions, just to get everyone on side.

Sorry about that - I thought i had, but tech skills must've failed me! I think i'm up and running now...

Got the radiator flushed at a mech. workshop - they said it was flowing freely and a bit mucky but probably not the cause of overheating. They also tested the emissions in the water - no signs of head problem but not 100% guaranteed. The radiator is only 2 years old and looks pretty good - a few odd bugs - the hoses are good - had them reviewed with the flush. I'm suspecting the fan.I tried what you suggested and no movement - feels very stable. As I understand it, I can replace the hub without replacing the whole unit. Is this wise?
Thanks heaps for the detailed options. Really good of you
Cheers

[YNOT]

You can replace the fan hub seperately, it is one possible cause.
It sounds like the radiator has not been cleaned properly to me, I would be removing it and taking it to a radiator specialist so they can remove the tanks and clean the insides of the tubes (rodding).
You also need to get a new thermostat fitted.

Tony

[Maxhead]

A mate of mine had his 3.0l in for overheating and the consensus was mixed coolants used. He thought it might a re-core.
I don't know if the 4.2 radiators can suffer from similar as they are very different ...but worth a mention

[Bigrig]

Make sure the thermostat you get is a 'cold one' - the valve on them opens about 10-12 degrees cooler when running - made a definite difference to mine.

[MQ MAD]

Defenately put a Thermostat back in
They are there for a reason , if ANYONE tells ya they run better without one,ask them whos paying for the new head youll need
Put the expansion tank back on,again they are there for a reason also
The water overflows to it then the radiator draws it back when required
IF its not there the excess water just pumps out onto roadway
Get the radiator profesionally rodded,no other method works as good as this
Cost about $100 depending if you remove and refit or the radiator shop does (more cost ???)

[thezig]

That's a good point. the last one was jammed shut and dry. Mongrel job to remove with a surprisingly long bolt in the housing.

[thezig]

Yeah i did that, put a brand new one on the hoses in the old one were pretty knackered. It's worth the cost - better than a new head!

[Finly Owner]

worst case scenario new radiator $380.00if roodding fails. Please go to reputable radiator shop.

Tim