VS 5 litre overheating troubles...

[Phreddy]

G'day there guys.

My VSII V-8 is getting too hot, but it's a bit of a wierd one....

It only seems to overheat when on the freeway, or during a sustained higher speed run for 20+ minutes or so. Putting around in traffic doesn't bother it too much. I've checked the obvious things, replaced the thermostat (cheap enough), and was about to do the water pump but after I'd removed it the one on the engine was fine. Full reverse flush of the block, radiator, and heater core, then refilled with brand new Nulon coolant at the correct dilution.

The radiator is a rconditioned unit, installed by Natrad about three months ago. (before I got the car) Therefore I'm not suspecting the rad, even though I suppose the symptom points to a partial blockage...(?)
(has anyone else experienced trouble with Natrad's work?? I though a reco radiator was pretty straightforward)

It's still carrying hte standard "clutch" fan - one thing I've noticed is that even when the engine is hot, there's not a lot of resistance when turning the fan by hand (with the engine stopped of course!) - I though these were supposed to "tighten up" a bit when they get warm.... ????

Question - does the fan clutch play up? Is it the sort of thing that can be suspect in a situation like this??? I'm toying with the idea of pulling the engine fan off anyway, and fitting a thermo electric fan...

Ummm - one other thing that I might mention.... I've fitted a set of headers (to replace the iron manifolds), and the fella I bought them off said that they shouldn't have a manifold gasket fitted.... I don't disbelieve him, but is that info incorrect?? (I wonder of a gasket provides some level of heat insulation, and if the headers are bolted straight up the heat from these is making the heads hotter - therefore heating the coolant more than it should be...) Dunno if that's logical but I'm running out of ideas.

Should I check the base timimg? (if it's too advanced, that would make it run hot, right?) Is it possible that there IS something wrong with the water pump, despit that it looks fine? (it's the type that has the cast iron impeller, not the cheaper spot-welded type) The bearing seems fine, and there's very little corrosion....

Anyhow, input welcomed.... I have to drive to Melbourne in a little over a week, will be a slow trip if she's always near boiling though...

Thanks guys!

[VrWagz1]

The only thing i can think of on for over heating on the freeway is the little peice of black plastic strip at the bottom of the radiator that directs air up into it might be missing. For some reason air dsnt really flow that well through the raditor while driving and that plastic thing helps direct the air up and creates some sort of flow
I would not suspect the clutch fan as that is the idea of a clutch fan, It stops spinning once your revs are up and you are moving as your forward motion moves the air through the radiator. Hope thats it anywayz. I could be way off yet though

[hako]

As above with the clutch fan - at highway speeds the air flowing thru the radiator from the movement of the car far exceeds the air moved by the fan. The manifolds should be OK without a gasket if designed that way. Maybe it's the temp gauge playing up or maybe it's quite normal - I know if I cruise at 125kph the gauge will be about 1/8 hotter on the gauge than at 100kphwhich is to be expected as the engine is working harder and needs to get rid of extra heat.

[delcowizzid]

excessive temp at cruising speeds can also be a damaged head gasket but ide be checking base timing first and also that theres no air trapped in the cooling system

[Phreddy]

Thanks for the input guys.... Yeah, I wasn't really suspecting the fan....

VRWagz - thanks for thap tip - I'll have a squiz at that.... And check the timing I guess.... Bloody hell, I hope it's not the gasket.... Bastard of a job....

Hako, understand your point, but it's a dramatic rise. The gauge gets up over 3/4, the engine temp warning chimes, and it does boil... Not violently, but enough... The crazy thing is that the trip I did to Brisbane a little over a month ago, it never missed a beat. Ran like a dream....

(by the way, I have looked for the symptoms of head gasket trouble - ie, water in oil / oil in water / bubbling in the radiator....)

Damn, need it to be right for this Melbourne trip....

[Phreddy]

Delcowiz - is there a process for bleeding trapped air from the cooling system? According to the Holden manual, there's no particular procedure... The radiator cap is the highest point in the system as far as I'm aware... I know there's a need to bleed the V6, but the V8??

(if there's a procedure, please enlighten me!)

[delcowizzid]

run it with the radiator cap off and the heater on hot untill the thermostat is hot enough to open and keep topping it up as required till its full and no air bubbles are seen appearing at the radiator filler neck

[VrWagz1]

phreddy, i done mine heaps an its very hard to actually get air trapped in the system on the 5ltrs. as you say the radiator cap is the highest point, but what delcowizz is good practice.

[hako]

How is the radiator cap - if it's not holding pressure it will boil however you say the hi temp warning comes on....bottom radiator hose collapsing at high revs and restricting flow?...why was the radiator replaced 3 months ago - probably due to overheating???....could the exhaust headers be somehow blocking the exhaust flow due poor manufacture....is the O2 sensor in the correct position on the exhaust....get a radiator shop to test your coolant for exhaust gas, this is a positive test.....

[Phreddy]

Thanks again fellas - DelcoWiz - thanks for the tip Mate, makes sense!

Hako - your suggestion is a good one too - reckon I might just do that. (coolant test...) It's possible that the bottom hose is collapsing I guess, wouldn't be terribly clostly to replace anyway.

Anyhow, here's hoping I guess. Cheerz!

[Phreddy]

Hmmmm, here's some funky extra info guys....

Had to drop my boys back to their Mum's place tonight - Oh, DelcoWiz - tried your procedure above, didn't really make any difference.... On the way home along the M4 though (which I'm on for 25 minutes or so) I found that turning the heater on full hot, it kept the engine temp manageable.... (baked the bollocks off me, but the gauge only climbed to just over halfway, instead of 3/4 or higher)

Does that provide any additional clues?? My logic tells me that if such a small "radiator" (ie - the heater core) is helping to cool the engine to THAT extent, then maybe I SHOULD be suspecting the radiator??? (or am I on the wrong track altogether??)

Thanks again for the help fellas.

[greenfoam]

The clutch fan should be alot stiffer when the engine is hot than cold, it's very noticable

[Phreddy]

Hmm, thanks Greenfoam.... That's the impression I was under - I though they should "firm up" when hot.... The one in the Statey doesn't really, it seems to pretty much "freewheel" all the time, even when real hot....

Although I would have thought that when I'm on the move at any decent road speed, that just the forward movement should get SOME wind through the rad.... Oh, VRWagz - yeh, that little "spoiler" is in place. It's a bit beat-up, but definitely in place. Hey Foam, is the clutch on the fan something that does fail after a while??

I did mention before that Natrad has serviced the colling system about 3 1/2 months ago, and a re-cored rad put in... I would assume that was done due to a radiator leak.... There were a lot of rusty water stains zround the front end, so.... Maybe the previous owner was a little careless about running coolant, and the radiator rusted through. (I assume the VS has a steel cored radiator?? Like the VN did AFAIK??) The water pump is is good nick (looks to have been replaced some time previous to the rad - little or no corrosion, and the bearing / seal are perfect)

(Ah, man - PLEEEEZ don't let it be head gaskets.... I'll be busy enough this week getting ready for Melb, let alone having to spend a day or two on replacing those bloody things! AHHHH!)

Anyhow, thanks again fellas....

[westbad]

i would be thinking head gasket
A few years ago i had a car with the same symptoms you describe and it turned out to be the head gasket.

[Phreddy]

Hmmmm, excellent. That would be just friggin' dandy.....

[hako]

Re the bottom hose collapsing - easy to test - run hot engine at 2500rpm and eyeball the lower radiator hose...maybe gently squeeze it to see if it collapses and watch out for the fan!
With all those rust stains suggesting major corrosion problems maybe the block has been dislodging rust particles which have clogged the radiator. Atest for a clogged radiator is to start with a cold engine, start and run engine at idle - have hand on thermostat housing to detect first warming which indicates thermostat opening - then with an infra-red thermometer (dick smiths ~$25) scan the radiator over every core tube as the hot coolant starts to flow thru the radiator and then over whole surface to ensure hot coolant is actually flowing thru all the tubes....if some areas of the rad are colder that indicates that the tubes in that area are blocked.
Of course you could just reverse fluch the rad and eng with the garden hose but that may not disloge everything.
And if you are really worried about a head gasket just throw some of that sealnt in the rad - that may temporarily seal a gasket leak.
These things always happen at the worst of times!!!

[Phreddy]

Hey, thanks Hako!

I'll give those couple of things a try... Just spoken to a mate who has a timing light, so I'll check the base timing tonight, as well as the bottom hose. Good point about the rusty water, I'll check that out. If Chemi-weld (or a similar product) will get me out of strife for the Melbourne trip, that might be the go if I can't find anything esle wrong.

One thing I have also talked to a radiator mob about is the fan clutch. I'm told that once the engine is warm, when it's shut down the fan should stop immediately - well it doesn't, it free-wheels for about a second or two. (which sort-of tells me that the fan clutch is buggered...)

See, my logic works this way - after running the heater made a significant difference - if an "extra" radiator / fan assembly (the heater core) is making that kind of difference, then I'm hoping to Christ that maybe I'm NOT dealing with a head gasket problem, simply some kind of inefficiency in the actual cooling system.... Either blockage in the rad, or the fan not pulling enough air through it. Put it this way - I'm much rather replace a fan clutch or a radiator than head gaskets! LOL!!

Anyhow, again guys... BIG THANKS!!

[VrWagz1]

I got an old clutch fan here if you need one. Its my old one so its not spectacular but it was working well when it came off.

[Phreddy]

Hey, thanks for all the help and suggestions guys!!!! I found the problem!!!

The BLOODY fan clutch - not picking up the friction at all, still freewheeling even when full hot. I did what's probably a bit of a stupid thing, but once I'd decided that the fan clutch was malfunctioning, I drilled a few holes right through and locked it up with some bolts. Re-fitting and going for a drive (keeping the revs reasonable low, as I'm not sure if such a big fan SHOULD actually spin as fast as the water pump....) and she stayed as cool as! Woo-hoo!

Wagz - thanks for the offer Mate, much appreciated - unfortunately you're not just "down the road" though, and my cash is a little tight at the moment - can't afford a trip to the 'Gong and back...

I'm playing with a 16" electric fan right now, but I don't think that has sufficient air flow - might have to go back to the mechanical fan for now - either get a new fan clutch or maybe a flexi-fan. (does anyone reasonably close to me have one they'd like to sell cheap? )

Anyways, again fellas - THANKS!! You won't believe how relieved I am that it's not head gaskets! PHEW!!

(gotta love this forum! )

[westbad]

Well done in finding the problem, pleased its not the head gasket.. im not to sure about your repair idea tho lol

[Phreddy]

HAH!!! Yeah, believe me I have no intention of leaving it that way!!

(Eeeew, it's horrible too.... It's been flinging all that silicone gel from the bolt holes all over the inside of the shroud...)

Seriously though, I just did that to confirm my suspicion - I'm replacing that clutch, or fitting a flexi-fan, over the next day or so. (depends on cost...)

But yeah, you bet I was relieved when I didn't have to pull the heads! Especially a few days before I have to head to Melbourne!

[westbad]

Good stuff ;-) easy fix for you.

[Cúl-Báire]

Hi All, and sorry Phreddy for bumming off your thread.

I am having similar issues in my 5ltr VT SS Commodore, I have replaced the coolant (full flush), hoses and thermostat, timing is fine; yet the car continues to struggle with overheating on sustained speed runs (i.e. highway driving) but while the car is putting around in traffic it is fine.

I have dropped the oil and found no traces of water in it, and there is no traces of oil in the coolant so at this stage I have ruled out the head gasket (please god, spare me that!lol). However I have noticed when the fans are operating, the drivers side fan is spinning rather slowly and spins more freely then the other one when the engine is hot.

Do the VT 5ltr's have clutch fans, and if so could this be the root of my overheating issues?.. I am running short of ideas!


Any help would be appreciated :-)

[ken007]

SPEAKING of overheatin & radiators, anyone know of a good place to get a radiator service / reco ? and how much am I looking at spending ?
Cheers

[hako]

Hi All, and sorry Phreddy for bumming off your thread.

I am having similar issues in my 5ltr VT SS Commodore, I have replaced the coolant (full flush), hoses and thermostat, timing is fine; yet the car continues to struggle with overheating on sustained speed runs (i.e. highway driving) but while the car is putting around in traffic it is fine.

I have dropped the oil and found no traces of water in it, and there is no traces of oil in the coolant so at this stage I have ruled out the head gasket (please god, spare me that!lol). However I have noticed when the fans are operating, the drivers side fan is spinning rather slowly and spins more freely then the other one when the engine is hot.

Do the VT 5ltr's have clutch fans, and if so could this be the root of my overheating issues?.. I am running short of ideas!


Any help would be appreciated :-)

As your overheating is occurring at highway speeds the problem will not lie with the fan(s) as above about 40kph, air coming in through the grille is greater than the air the fans produce.
I'd be looking at the radiator being partially blocked and in need of a reverse flush. If the car is high mileage you can expect it to run hotter.
Another thought - do you have spotties in front of the grille? - they can block the flow of air thru the radiator at speed