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TR7 V8 Overheating


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Hi there, as newbie TR7 V8 owner, I have acquired a recent conversion with (I think) an SD1 V8 which on a recent run round the M25 and M3 at a steady 50-70mph (yes even on the M25!) the temp gauge showed N but upon stopping at Fleet services some steam wisped out. Opened the bonnet, and much steam, quite a bit from around the exhaust manifold, and loosening the overflow tank cap, a lot of pressurised hot water spurted out.

 

So the car has new rad, twin fans (which are working) , the heater still pumping out hot air into the car, belts tight, but the coolant (which was replaced only a few weeks back) looks dark (& dare I say it, oily) but no sign of creamy deposits anywhere.

 

I did notice a couple of strips of (what looked like) red elastic band being ejected with the coolant suggesting a gasket has gone somewhere in the system.

 

Ideas welcome, but I am thinking I need a new thermostat, and/or water pump, not least as some evidence of wetness on the low cross member under the front of the engine.

 

Thanks!

 

 

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  • 2 months later...

Air locks in the top hose can often be a problem. To specifically address air lock problems,

 

1) you need to drill a 3mm hole or two in the thermostat to allow the air into the top hose even if the thermostat is closed.

 

2) it makes it a lot easier if you fit a forging with a vent plug in the top hose to let the air out as you fill up, and add the last little bit of water direct into the top hose to get it really full. You can get the forging from revotec and it takes a standard 3/8 bsp plug.

 

If you have overheating probems, also make sure the radiator cap seals OK since this will aggravate them.

 

There's quite a lot on this forum and on others abut Rover V8 overheating. I think the TR7 installation can be quite prone to it. In my Grinnall the top of the top hose is actually above the top of the header tank, making it more difficult to fill.

 

Good luck.

Al

 

.

 

 

 

post-10663-0-46237500-1513008856_thumb.jpg

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Detach the header tank, and hold it up in the air whilst filling . . . . that generally shifts the usual airlock resulting from the thermostat and/or top hose being above the header tank as mounted.

 

If the engine has got that hot, as in steaming under the bonnet, then you've almost certainly cooked it by now - the water pump and thermostat may be OK, the gaskets around them probably not.

 

If the head gaskets haven't blown already then they soon will, so you might as well get on and renew them anyway . . . . . . they never last long once a V8 has overheated.

 

Cheers

 

Alec

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  • 4 weeks later...

Thanks for all the help and advice. Issued sorted and I feel something of a numbskull. Yes then engine was getting hot but what I took to be steam/boiling coolant was actually oil burning off - the car had a big oil leak which has now been sorted and problems resolved...well this one at least!

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  • 11 months later...
On 12/11/2017 at 4:15 PM, acaie said:

Air locks in the top hose can often be a problem. To specifically address air lock problems,

 

1) you need to drill a 3mm hole or two in the thermostat to allow the air into the top hose even if the thermostat is closed.

 

2) it makes it a lot easier if you fit a forging with a vent plug in the top hose to let the air out as you fill up, and add the last little bit of water direct into the top hose to get it really full. You can get the forging from revotec and it takes a standard 3/8 bsp plug.

 

If you have overheating probems, also make sure the radiator cap seals OK since this will aggravate them.

 

There's quite a lot on this forum and on others abut Rover V8 overheating. I think the TR7 installation can be quite prone to it. In my Grinnall the top of the top hose is actually above the top of the header tank, making it more difficult to fill.

 

Good luck.

Al

 

 

.

 

 

 

post-10663-0-46237500-1513008856_thumb.jpg

There are lots of threads on TR7V8 overheating on TRR  and on TriumphTR7.com. My contribution to a relatively recent one is above. One other thing I discovered relatively recently was that my heater was leaking, so I bypassed the heater with ordinary 15mm piping and that made a substantial reduction in the running temperature. 

Best wishes

Al

 

Edited by acaie
posted in wrong thread
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On 1/8/2018 at 3:26 PM, TReslaV8 said:

Thanks for all the help and advice. Issued sorted and I feel something of a numbskull. Yes then engine was getting hot but what I took to be steam/boiling coolant was actually oil burning off - the car had a big oil leak which has now been sorted and problems resolved...well this one at least!

Well done, I'm sure you're relieved that it's not a head gasket.

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  • 2 years later...

Hi,

I've  just fitted a 3.9L in to my TR8 convertible taken out of a Discovery which has been skimmed and fitted with new head gaskets. I've fitted it with a four barrel holley carb, so my return has gone. I've made a joiner up top hose for the return to the header. The problem I'm having is the water doesn't seem to be circulating, which causes the water to get hot. It then starts pumping out of the header tank, or with the cap on pressurises the hose, which goes rock hard so the cap gives way.

I don't have any pictures or diagram of how the water system should be so I'm just guessing!

The original -P6 engine (with SDI heads) was putting exhaust gasses into the header tank. I had the heads skimmed but there was no difference! I thought it was the liner seals. Hence me going for 3.9 engine.

I'm at my whit's end so any advise or help would be much appreciated.

Thanks,

Paul

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Looking at the top hose configuration I would think about it air locking. The vent you have connecting to the expansion tank looks too low down to get the air out. If you can get it at or much nearer to the highest point in the top hose it may help.

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Well the obvious answer to your question is that the radiator is blocked.

A messy test for that would be to disconnect the top and bottom hose from the rad. Then use the garden hose in the top hose position and check the water flows. Might be worth doing the reverse while your at it then again from the top. That should give it a bit of a clear out anyway.

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