Overheating

Cobber · Postby **Cobber** » 21 Jan 2009 10:52

Of course the other possible solution to overheating is a thematically controlled electric water pump.
When you think about it our engine driven water pumps are hardly working in heavy traffic at idle and low RPM when we need them most!
And they pump like all buggery when we have good air flow and don't need them as much! So these Davies Craig pumps might be the answer!
http://www.daviescraig.com.au/main/display.asp
I've purchased one at will give it a go, but I can't say when I'll have time to fit it. I'll try it out on one of my other more expendable cars first so I it's not up the job I wont be risking an engine I care about!


80'Triumph TR7, , 73'Land Rover (Ford 351. V8),
'89 Ford Fairlane
85'Alfa 90, 69'Ford F250.
76' Ford F100

Odd · Postby **Odd** » 21 Jan 2009 11:11

<blockquote id="quote">quote:<hr height="1" noshade id="quote"> Hasbeen also mentions Engine oil coolers and ... the problem I can see is finding somewhere to mount it
with out blocking or increasing the temp of air flow through the radiator. <hr height="1" noshade id="quote"></blockquote id="quote"> That's the reason I fitted my oil cooling (as did LR in the donor Disco!) into the water cirquit!
No extra radiator and just two puny pipes/hoses from the oil pump to the [cold] radiator tank
and back. Simple, out-of-the-way, and remeber the heat transfer capacity is much higher per
unit of contact area for fluid-to-fluid as compared to fluid-to-gas...

jclay (RIP 2018) · Postby **jclay (RIP 2018)** » 21 Jan 2009 12:24

Why not mount an extra, very wide radiator as a rear wing! It could happen!

jclay

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Hasbeen · Postby **Hasbeen** » 21 Jan 2009 18:13

Cobber, that Darwin car is one of the few road cars, in Oz, where
the rear wing was something other than pose value.

Up until last year the Northern Territory was the only place in Oz,
with a sensible speed limit, on open roads. NONE. With that engine
the car should have been capable of over 145 MILES per hour. That
spoiler may have been some use at that speed.

Back to temperature, do all 8s run up to over 5/8 on the gauge,
before the thermostat opens? Once it opens the temp drops straight
back to 3/8, in less than a minute, so I doubt the engine is getting
hot, but perhaps an earlier opening stat would be in order.

One side light on engine temperatures, I recently had to buy a new
thermostat for the 7, as the gauge refused to get up to even 1/8 no
matter how the car was driven, even in this summer heat.

I think it must have stuck open, as with the new one fitted, the
thing runs at about 1/4, on the gauge. It is really nice to have one
car that deosn't overheat.

Hasbeen

Underdog · Postby **Underdog** » 21 Jan 2009 18:52

FWIW, Mine has the stock TR8 radiator and dual cooling fans. It normally runs up to about 5/8 (a little above half) It will fluctuate a bit between there and 1/2 as the fans cycle. I run a 195 thermostat. Haven't had a problem with any overheating at speed. I haven't done a track day with it yet though. Waiting for spring till that happens.

Most vehicles I've owned ran hotter at highway speed than at idle. Engine just generates more heat at higher RPM. My guess is your radiator isn't up to task. Either too small or partially pluged.

72 MGB BRG
80 TR8 Persian Aqua
If women don't find you handsome, they should at least find you handy.

windy one · Postby **windy one** » 21 Jan 2009 19:46

I had a very similar problem with a vehicle recently. Not a wedge, but the symptems sound the same. Full size one-ton truck. Xtra-Xtra heavy-duty cooling system & trans cooler. (temp) Gauge never moved neither during extended idle nor normal driving...hot or cold outside. Soon as I would begin to work it (i.e; drive hard) it would get sooo hot it almost overheated. Shouldnt have happened with such a large cooling system but it did.

When I tore the engine down, turned out corrosion in the cooling system (actually looked like mud!) was seriously hampering the flow of coolant. At idle/normal drive it was ok, push it hard and the coolant couldnt flow properly to cool.

One thing I have learned about the 3.5L V8 being all-aluminum (actually every aluminum engine) is that you should Not use ordinary tap-water to dilute the coolant, use distilled water. Tap water will cause premature corrosion in aluminum engines.

hope this may help you even a little...J-

Johnny

PeterTR7V8 · Postby **PeterTR7V8** » 31 Jan 2009 05:52

Help!! I put in a new electric fan & it tested all ok but after a drive today the fan failed to turn on. After a bit of testing I found I'm getting just 3V from the relay to the fan.

I have a thermo switch which clicks as it should & all the wiring has not changed from the old fan. I swapped the relay but same result. Why would I be getting 3V out of the relay??

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Cobber · Postby **Cobber** » 31 Jan 2009 06:41

Sounds like a bad connection, Whats the voltage feeding the relay? I don't mean the switching current I mean the main feed from the battery.

80'Triumph TR7, , 73'Land Rover (Ford 351. V8),
'89 Ford Fairlane
85'Alfa 90, 69'Ford F250.
76' Ford F100

PeterTR7V8 · Postby **PeterTR7V8** » 31 Jan 2009 10:04

Thank you Cobber. Would you believe it was 3V too. The line goes directly to the +ve terminal & the inline fuse holder had melted a bit. I couldn't uncouple it because the two pieces had become one so I cut the wires & have new spade connection on without a fuse for now. It works but I have to wonder why the plastic fuse holder melted. It could only be 1 of 2 things. The draw from the new fan or the fact it has sitting on the wiper motor long enough to deteriorate to this brittle half melted state. Even though I haven't used the wipers since installing the fan yesterday I think it might be the heat from the wiper motor. I have a 7.00am start tomorrow for a hillclimb so I don't have time to get a new fuse so I'm hoping it will last the day.

Got a nice HT shock in the wrist when I knocked the lead of the coil while fiddling with the wires with the engine running.

This was all in the name of curing this overheating problem. Someone suggested that the old fan with its fat 4 blades was not the best so I put the new fan on using all the existing wiring. I also piped the overflow spout from the radiator to the header tank which has what looks like a pressure relief valve. But when the fan stopped working I found out that the valve doesn't work so instead of relieving itself from the spout the water just came out from the radiator cap in a fairly dramatic fashion. The plastic header tank is from a Holden I believe. I've disconnected the spout hose from the tank for now but surely the header tank cap should blow off pressure before the radiator cap does.

I have also borrowed a capilliary temp gauge to get a true reading on my water temperature. At 7/8s on the dash gauge the water temp is 115C so does that suggest that the sender is too sensitive or is it about right?

This is the problem when you buy a converted car. You have no idea whether the new bits are working correctly.

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Workshop Help · Postby **Workshop Help** » 31 Jan 2009 14:05

Just a thought here, may I suggest the use of a temperature gun to determine the true temperature of the coolant as it exits the engine thru the thermostat housing?

It's painfully simple. Once the car has reached it's hottest running temperatute, aim the gun at the thermostat housing. If the reading is anywhere close to the rating of the thermostat, you're OK. Also, check the temperature of the bottom radiator hose. There should be a significant drop in temperature. Also, check the heater hose as it leaves the engine and it's reading on the hose exiting the heater core.

This is a very useful tool.

Mildred Hargis

PeterTR7V8 · Postby **PeterTR7V8** » 31 Jan 2009 17:07

I'm ahead of you there, Mildred. I borrowed a temp gun on Friday & found that the radiator was working well. My problem seems to be that the expansion tank cap does not release pressure so the pressure builds up in the radiator until it escapes through the rad cap.

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PeterTR7V8 · Postby **PeterTR7V8** » 31 Jan 2009 20:20

Well I have gotten thru practice & all seems to be holding together. The fan is working, the water is staying in the radiator & the wire to the fan relay is not even warm.

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Workshop Help · Postby **Workshop Help** » 31 Jan 2009 20:34

A bit of confusion, are you saying the radiator cap is not releasing pressure at the indicated amount on the label?

Back in the old days, we used to replace radiator caps all the time.

Mildred Hargis

Cobber · Postby **Cobber** » 31 Jan 2009 22:34

Does the radiator cap have the correct pressure rating?
Is it's pressure rating less than that of the header tank cap? If so that would explain why it releases first.
Is your cooling system over pressurising because of another reason? Maybe a stuffed thermostat or worse a blown head gasket or cracked head?
First just replace the radiator cap they're cheap, while ya at it ya may as well replace the thermostat too!
Then you need to establish that your not getting combustion gases leaking into the cooling system. I suggest you do both a compression test and a radiator pressure test at the same time.

80'Triumph TR7, , 73'Land Rover (Ford 351. V8),
'89 Ford Fairlane
85'Alfa 90, 69'Ford F250.
76' Ford F100

tr8coupe · Postby **tr8coupe** » 01 Feb 2009 07:21

[:D]running to high temperatures results in 1 cracked blocks 2 slipped liners and 3 lower power [:p]

1 and 3 afects all engine sizes 2 afects all sizes except 3.5 lol

BMW Z1 ( sold)
Westfield sport carbon (sold)
Eurosport x1/9 turbo (sold)
TR8 coupe
TR7 v8 monster on 245 tyres all round (sold)
TVR VIXEN

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Overheating

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