VH cooling problem

[DerekP]

G'day folks

Got a problem with cooling my 5.0 VH. As previous posts have described, on a hot day with the A/C on the temp gauge just keeps rising - it's fine in cooler weather or if the A/C is not being used. I have just had a brand new 3 line radiator fitted and it seems to have only marginally improved the issue. The clutch fan appears to be fine, and the water pump has no noises or leaks and the thermostst is fairly new. The transmission however gets hot, you can feel the t-bar getting hotter and hotter inside the cabin and I'm not towing anything or loading up the car with weight. I don't know if the tranny is heating up the radiator or vice versa. I am not sure what to try next - I was thinking of gettting a decent sized tranny cooler? Any suggestions or advice would be greatly appreciated.

The car is a VH SL/E 5.0 auto - completely stock except genie headers.

Cheers

[ari666]

first things first, you should check your timing and spark gap cos' too far retarded timing can cause overheating. as can crap spark gap.

but yeah, its possible that your trans fluid is cooking your radiator through the side tank, you should check that the fuid is flowing freely and not restricted. if it is the case that your fluid is hot enough to cook the rad, i would be more worried about whats going on inside the trans that would make it that hot... i am running a crap EL (i think) falcon transcooler which were factory recalled and made to fit bigger trans coolers. got it for 10 bucks. after a long drive you can still hold the cooler for a few seconds without it burning i.e. the fluid isnt overley hot. totally bypassed the rad and running 2500 hi-stall.

what colour is the fluid? what does it smell like? is it full? slip out of gear around hard corners then thump into gear again suddenly?

[DerekP]

what colour is the fluid? what does it smell like? is it full? slip out of gear around hard corners then thump into gear again suddenly?[/QUOTE]


The trans fluid is new on account that I had the speedo drive gear replaced only a few weeks ago - same time the new radiator went in and it was done buy a reputable (alledgedly) auto shop in my area. For a traumatic it changes quite well with no obvious issues that I can detect - except it does gets a little temperamental after/during overheating but generallly the tranny seems fine.

[ari666]

hmm. ok, well TBH i wouldnt be looking at your trans cooking your system anyways. i have not heard of it b4, i guess it could happen but i find it unlikely.

ok, so if you can answer these it will help heaps;

do you have TVS attached and working?
how is your vac advance connected if it isnt working.
what is your initial timing set on?
what condition is the dizzy in?
what sort of vac readings are you getting in-gear at idle.
where is your timing in-gear at idle.
whats the condition of spark plugs/leads/rotor button.

also what PSI radiator cap are you using?
any water leaks that you can see around your cooling system, i.e. small dribbles of dry white stuff. *edit, you mentioned the pump isnt leaking, i am talking more about hoses, heater fittings, inlet manifold temp sensor, radiator fins, overflow hose, radiator cap etc etc etc.
dos your overflow spit coolant everywhere
what coolant you using.
does the temp go down when you switch the heater on. if yes how dramatically does it drop.
using a shroud?

lol, sorry to hit you with it but all thise things need to be considered. i would probably work in the order of the questions too cos' it sounds like you have done everything but the tuning, which can be the downfall of a cooking car.

p.s. EVERY time you go over 3/4 temp you should change your oil. a lot of people would say its unnecessary, but oil keeps your engine cool, and once its cooked it doesnt work as well.

[DerekP]

Firstly, thank you for taking the time to consider my cooling problem and posting a comprehensive trouble shoot list, it is hugely appreciated.

Now obviously your mechanical knowledge far exceeds mine so please excuse me if I seem like a complete novice and ask dumb questions, however I will attempt to try and answer to the best of my knowledge.

Sorry but I don't know what a TVS is (not a great start!).

The vac advance & timing settings / readings - I don't know but I do know that the car performs very well, powerful (for a stocky) and does not use excessive juice (LOL!) for an old girl. The dizzy itself seems fine and I replaced the dizzy cap, rotor, plugs and high tension leads about 6,000km's ago. The car generally is in very good condition - only 150,000km's on the clock and I am only the second owner (bought off an old guy in QLD who had it since new...). I don't thrash it either (just in case you were wondering!!).

The rad cap is standard and there are no coolant leaks of any kind, I have made a point in monitoring this closely and never need to top up - even after overheating! If there is one thing the car does not do is loose coolant... All hoses are new or are in very good condition. The temp sensor seems to be fine i.e. seems to send the correct temp info to gauge (when it's hot it reads hot!!) and the coolant does not flow out of overflow unless it has been overfilled. The radiator fins are good as the radiator is brand new - about 30k's old. I don't know what type of coolant is in it as the mechanic replaced it when he did the radiator but I assume it is good stuff as he charged accordingly! The temp does go down somewhat when the heater is turned on but I would not say significantly. The clutch fan has the standard shroud and the auxiliary thermo fan works also.

I would probably need to take the car to a mechanic to check timing and vac settings etc as I don't have the expertise or tools, so perhaps I will do that. I am still considering getting a tranny cooler fitted in any case, can't hurt right?

Thanks again

Cheers

[ari666]

no such thing as stupid questions, only stupid people, and you dont seem like a stupid person so were OK

TVS stands for thermal vacuum switch, it is located on the front of your inlet manifold an has 4 tubes going into it. there are two tvs's on the inlet manifold and from memory the one which does timing is on the drivers side of the car. have a quick look at whether all the hoses are plugged in to that switch and in good condition, i.e. no holes or cracks.

if the hoses are not connected to the TVS its is no big deal. i bypassed mine within 5 minutes of owning my car cos' i think they just introduce more potential problems. anyway, if tvs is bypassed, then you need to look at the vacuum advance on the dizzy. the dizzy has a silver cylinder thingie on the side of it with one vacuum hose coming off it. trace that hose and it should lead to the carburettor and be plugged in here:

that is ported vacuum. now, you may have a slightly different carby cos' quadrajet made 3 million different kinds, but dont stress. finding the ported vacuum port isnt hard. with the engine running at idle disconnect a hose lick the tip of your finger and block the port off. if you feel suction, then its a full vac port and not the one you are looking for. if there is no vac, rev the engine up pretty hard just once while blocking the port. If when the engine is dropping down revs you feel suction, then thats your ported vacuum.

now the reason i go into detail on this point is from my own expierence. in the days when i was using full vacuum to make my car go faster, i drove up to the country for a weeked. the faster i went on the freeway the hotter my car got, so when i was going 110 (national speed limit) i was getting up to 3/4s temperature. so i was forced to drive 80kmph the whole way and temp was on 1/2.

when i got to my destination, i decided to run ported vacuum and retuned. on the journey back she never got hotter than 1/2 and i was bombing it down the freeway.

so my point is that you sound like your cooling system is all sorted, but you may have the same prob that i had. someone has swapped to full vac, and its not getting enough advance at part throttle to keep the ol' girl cool.

p.s. yeah fitting a trans cooler wont hurt either, but people on here say to hook up the flow; radiator first, then the trans cooler, then back to trans.

[180sc]

Does it have an electric assist fan in front of the radiator-a/c condeser? does it work when the a/c is on? If no to either id recommend fitting a good quality after market unit to the front of the a/c condenser and make sure it pushes air through the radiator not sucks.
Check your thermostat is there and working correctly.

Another note get an aftermarket transcooler they are better than the radiator ones and temp is a transmissions worst enemy. you can run through the rad as well or run it independent, personally i dont run it through the rad as in my opinion its not gunna be as effective with the rad heating it.

[DerekP]

so my point is that you sound like your cooling system is all sorted, but you may have the same prob that i had. someone has swapped to full vac, and its not getting enough advance at part throttle to keep the ol' girl cool.

p.s. yeah fitting a trans cooler wont hurt either, but people on here say to hook up the flow; radiator first, then the trans cooler, then back to trans.[/QUOTE]

Thanks ari666, I will take a look at the vac system over the weekend and see how I go - with your notes close by !!!

Nice one

[DerekP]

G'day mate, yeah it does have an electric condensor fan on the front and it works but you have raised a good point as to whether it is pulling or pushing the air through the rad - I will definitley check that. The therostat switch is there also - drivers side of the radiator.

A trans cooler is definitley on my shopping list!!

Thanks.