TR4 engine running hot

[Westy]

I have read a few posts about possible causes for engine running hot on a TR4A. I have recently had an unleaded head fitted and the garage flushed out some crud that had collected at the bottom of the water jacket. At the same time the thermostat was reconnected (disconnected by previous owner!) and engine found to be running hot, just touching the red marker but with no steam or boiling over from the rad. Had the rad checked by auto radiator specialist repairer and flow was good but took the end off and rodded through to ensure 100% clear. Fitted a new thermostat and checked all the hoses. Car runs cooler with heater on - about mid-way between normal and hot. The car has a replacement water pump from Rimmers but I hear these are cheap Indian made repros and that reconditioned original with brass impeller (not cast iron) is the way to go. I have an electric fan but have to activate manually as the thermostatic switch doesn't work (anyone know where I can get a replacement?). Should I re-fit a belt driven fan? The temp gauge seems to be working OK as it starts reading cold and moves slowly towards hot as the car heats up. No discernible effect on how the car runs. I refilled the car with de-ionised water went for a short 5 mile drive and topped up with about half a pint when I returned. Anyone got any ideas? Could it still be an airlock? The sun is shining and I am missing perfect driving days!

[MikeF]

I have read a few posts about possible causes for engine running hot on a TR4A. I have recently had an unleaded head fitted and the garage flushed out some crud that had collected at the bottom of the water jacket. At the same time the thermostat was reconnected (disconnected by previous owner!) and engine found to be running hot, just touching the red marker but with no steam or boiling over from the rad. Had the rad checked by auto radiator specialist repairer and flow was good but took the end off and rodded through to ensure 100% clear. Fitted a new thermostat and checked all the hoses. Car runs cooler with heater on - about mid-way between normal and hot. The car has a replacement water pump from Rimmers but I hear these are cheap Indian made repros and that reconditioned original with brass impeller (not cast iron) is the way to go. I have an electric fan but have to activate manually as the thermostatic switch doesn't work (anyone know where I can get a replacement?). Should I re-fit a belt driven fan? The temp gauge seems to be working OK as it starts reading cold and moves slowly towards hot as the car heats up. No discernible effect on how the car runs. I refilled the car with de-ionised water went for a short 5 mile drive and topped up with about half a pint when I returned. Anyone got any ideas? Could it still be an airlock? The sun is shining and I am missing perfect driving days!

 

 

Hi Is this a recent acquisition? Do you know if all was OK before you changed the head?

Open the heater valve before refilling/topping up, run the car and refill. Do put summer coolant/antifreeze in your cooling system when you have finished sorting this. DI water on its own will not stop corrosion. (Actually DI can be quite corrosive).

If it isn't boiling over or steaming or losing coolant or running on, then it it could be because it isn't overheating and the gauge is wrong. This is pretty common, check out posts on voltage stabilzers in this and general forums. If it is not working/absent then the temp and fuel gauges will read high as the stabilizer feeds both with a 10V supply. Try dipping the tank and relating to gauge reading. A replacement will cost £10 or less. Alternatively if you are handy you can make one yourself for £1.00 or so for parts.

I think the majority opinion is that with a sorted system and electric fan you don't need the mechanical one.

 

Mike

[Westy]

Hi Is this a recent acquisition? Do you know if all was OK before you changed the head?

Open the heater valve before refilling/topping up, run the car and refill. Do put summer coolant/antifreeze in your cooling system when you have finished sorting this. DI water on its own will not stop corrosion. (Actually DI can be quite corrosive).

If it isn't boiling over or steaming or losing coolant or running on, then it it could be because it isn't overheating and the gauge is wrong. This is pretty common, check out posts on voltage stabilzers in this and general forums. If it is not working/absent then the temp and fuel gauges will read high as the stabilizer feeds both with a 10V supply. Try dipping the tank and relating to gauge reading. A replacement will cost £10 or less. Alternatively if you are handy you can make one yourself for £1.00 or so for parts.

I think the majority opinion is that with a sorted system and electric fan you don't need the mechanical one.

 

Mike

 

[Westy]

Thanks Mike. After all this I simply removed the thermostat this afternoon and went for a drive to test - everything seems fine and maintaining a normal temperature. The thermostat was recently fitted by a garage and is the cheaper wax? type (about £5) so I assume was faulty but haven't tested as I don't own a thermometer! Any opinion on whether I should leave the thermostat out or replace with a bellows type? I spoke with Paul at Enginuity (very helpful) who suggested I put in a lower temp (74 deg?) thermostat (the one I removed was 82 deg). Grateful for any advice. I am a new TR4A owner but have owned a couple of 6's in my youth.

[Lord Flashart]

If they fitted a modern thermostat did they restrict the bypass on the side of the thermostat housing? If not this could be your problem.

 

Paul

[RogerH]

Hi Westy,

you could check the temp bulb by putting it in a pan of hot water and see what the gauge reads.

Like wise the thermostst can be checked in this manner.

If the engine is getting hot and you need to do extra things to keep it cool then it looks as though the area around #4 pot is bunged up with crud. Poking rods through water holes will not shift it.

 

Most of the usual suppliers do thermostats for your fan.

 

You don't need the mech fan.

[Bully]

I had an overheating problem many years ago in my TR4A. It turned out to be a blockage in the water ways between No4 cylinder and the block.

 

It would appear that over the years, people have drained the water out of the engine just by using the valve on the bottom of the radiator, and ignoring the tap on the block just above the starter motor. This leaves a lot of water and sediment in the block. When you drive along, this sediment gets pushed behind No4 cylinder, and eventually blocks the waterways.

 

One test is to open the tap in the block to see there is good flow out. if not, then this is a sign of blockage.

 

Another test, is to see that when the engine is overheating, is the bottom hose cold? As the water can't circulate, it superheats, and comes back past the water pump (even thought it is good and working well), and blows out of the radiator cap.

 

To solve the problem, take off the cylinder head, bend a thin wire to form a spoon, and dig out the rubbish behind No 4 cylinder. Be careful not to disturb the cylinders in their seals.

 

Good luck

 

Bully

[Westy]

Thanks to all those that replied. Borrowed a thermometer from a neighbour and tested the thermostat but opened OK at 84 deg so not the problem. Removed the rad cap and opened the drain tap above the starter motor and water trickled out, reasonably clear but some rust-like particles/sediment. Called the previous owner who confirmed that water gushed out when he last drained (about 2 years and 2k miles ago) so seems like it could be a blockage behind no. 4 cylinder (that's the one closest to the battery right?) as suggested. Or should I disconnect a hose somewhere to relieve the pressure and open tap again before going down this route? He also confirmed that he replaced the water pump (which I also unwittingly did) so I think ruled that out. I'll let you all know how I get on if you haven't tired yet - stay tuned!

[BrianC]

Best option is to flush and back-flush the whole system via as many points as possible by removing drain tap, heater hoses, etc. Be prepared to spend a couple of hours playing with a hose-pipe and getting very wet, but it's worth the effort. It makes sense to do this whenever you change the anti-freeze

 

 

[Bully]

Hi Westy,

 

only a trickle from the drain tap does imply a blockage behind No4 cylinder (nearest the bettery).

 

Take the tap out, and feed the thin end of a cable tie in at an angle towards the battery and have a rummage around. The cable tie is stiff enough to move some sediment, but not hard enough to do any damage. If you get a good flow, then keep flushing and you may be lucky.

 

If you can't get a good flow, then i would recommend taking the head off and digging it out to get a good flow.

 

Cheers

 

Bully

[Westy]

Thanks Bully - I'll give it a go and tell you how I get on.

[Mark1965TR4aBRG]

Read this with interest, as I've just started to drive my 4a after a complete re-build (engine too).

 

My temp guage is irregular, although does now appear to be behaving. However as soon as I slow or stop @ lights, the needle raises quick quickly - doesn't get to 100 and I only have the mechanical crank shaft plastic fan, no leccy fan.

 

I got back last night and it was ~30deg ambient and tested the temperature of the sensor and it was 74C. This was measured with the guage reading ~70, so I figure actually I'm OK with engine temperature, but will fit the leccy fan.

 

Question: Is the temp rise in traffic quick on all cars.

 

I have refreshed the coolant, flused the system out and get good clean flow just about everywhere. I run 50:50 anti freeze/tap water - is this right? No coolant loss and a nice full system..

 

Thanks

[Ade-TR4]

Might be worth double checking mixture/ ignition timing. Plus, what mech stat have you in the engine? (original type with bypass cutoff, and what temp rating?)

 

If the temp comes back down when you get going again, I'd say it's probably OK.

Electric fan is a must in modern traffic: You don't know when you're going to be at a standstill or for how long!

 

Cheers

Adey

[Westy]

Having re-read this post I have obviously missed a point that two owners have made re; thermostat bypass. The thermostat I removed was the cheap variety but I purchased a bellows type which I have not yet fitted. My question is: how does the type of thermostat you fit determine whether to block the bypass? On a separate but related point re; cooling I was told by a specialist auto radiator repairer with 30 year's experience that ally radiators give no cooling advantage and water is the best coolant - so I guess no need for additives unless to lower freezing point in winter?

[ianc]

Having re-read this post I have obviously missed a point that two owners have made re; thermostat bypass. The thermostat I removed was the cheap variety but I purchased a bellows type which I have not yet fitted. My question is: how does the type of thermostat you fit determine whether to block the bypass? On a separate but related point re; cooling I was told by a specialist auto radiator repairer with 30 year's experience that ally radiators give no cooling advantage and water is the best coolant - so I guess no need for additives unless to lower freezing point in winter?

 

 

If you fail to use a good anti-freeze in the water, corrosion inside the engine block (where you cannot see it happening) will be rapid. For this reason, Anti-freeze should be used all year round, with a stronger mixture in winter if you live in a really cold country.

The alternative is to flush the system to remove all traces of rubbish, remove all anti-freeze/water and get the system as dry as possible, then install Forlife (neat). This is the fluid recommended by the late Dr Michael Bingley and used in his TRs, both of which had water passages which were as new.

Thermostat: put a metal or plastic bung (with a small hole through it) inside the bypass hose and use whichever type of thermostat (bellows or waxstat) you want.

Ian Cornish

[Westy]

Thanks Ian. I live in Great Missenden and see you are in Aldbury so if you are willing to look over my car and lend some much needed advice I'd be very grateful. I bought it about 3 months ago and just getting to know it. Have owned a couple of 6's so not completely unfamiliar with Triumphs - I think I saw you at the Weston Turville car show last year if you own 4VC. Just let me know.