Christmas run - overheating!

[Ogrodz]

Hi folks. Took the TR6 out for a blast after not using for a month. Everything was fine (oil pressure normal, temperature normal, fan working) until I pulled back into the drive at home - then the temperature gauge started to climb. Kenlowe fan was on, but the car overheated.

I switched off, let the engine cool down for 15 mins or so, then restarted. All seemed fine temp wise, then sudden quick rise in water temp, kenlowe fan kicked in but not able to deal with the rising temp.

The car has always been freezing in the cabin - no heat - on investigation I noticed that the heater cable was not connected in the engine bay and also on squeezing the pipes going into and out of the heater box (engine side) I noticed a "crunchiness" - possibly crud in the pipes??

So, I am suspecting that after a months standing, some crud has been dislodged and is blocking the free flow of coolant - causing overheating. Does this sound reasonable?

Before I get my spanners out - I would appreciate some advice on how to prioritise the troubleshooting.

Would the first step be to drain the coolant, look for crud, and try to flush out the system? I assume using a hose?

If this doesn't work, would you advise thermostat next, then pump, then radiator?

Thanks in advance for your suggestions.

Happy Christmas!

 

 

 

 

[John Morrison]

If the car ran OK but temp shot up on Rickover I,d be thinking water pump.

check fan belt isn’t slipping and if there is rock on the pulley 

I,d also locally repeat a run to see if air going through the rad keeps temp ok but standing causes the probs.

John

[Z320]

+1 for water pump and belt, but the charging control lamp was out?

Charging and Ampere gauge was fine (than not the belt)?

Did you have real temperature problems or was the sensor / gauge / voltage stabilisator not proper working?

Next I would take the thermostat out for a test drive without.

Heating will maybe limited more this way, but cooling must work.

Do step by step to be shure to identify the reason.

Ciao, Marco 

[Mike C]

Are you sure the fan is working correctly and has the correct capacity? Cooling OK on the freeway then overheating when  stationary points to a fan problem.

If the fan's OK.I've found a quick rise in temperature is generally an airlock, there are many posts in the forum on how to deal with these and the methodology is different for different TR6 models .

You shouldn't have crud dislodged if the engine coolant/antifreeze is of the correct concentration and still within its use by date. Many TR's are left over winter unused and restart in spring without radiator sludging problems.

If you have no airlock, I'd take out the thermostat and check it by heating it in water checking the opening temperature with a thermometer. Make sure your thermostat is one fitted with an air vent hole- if it hasn't got an air vent drill a 3mm hole in the valve.

Next step I'd take would be to backflush the radiator and heater- again there are instructions for this on this forum. Make sure you run the engine for a while after you refill it with the radiator on full heat to remove all the air from the radiator core.

If the heater hoses were crunchy within 25mm or so of the firewall, you've probably broken bits off the mild steel coupling that joins the heater pipes inside and outside the cockpit- the broken coupling bits shouldn't affect the cooling but may leak later.

Edited December 25, 2022 by Mike C

[Ogrodz]

Thanks for your quick replies:-

In order:-

John Morrison - the fan belt doesn't seem to be slipping on the water pump

Z320 - the charging indicator seems normal - no issues with alternator

- I conclude that it is unlikely to be the water pump / loose belt

Z320 - is it a real overheating problem? - yes, left to idle and overheat I quickly get a jet of steam coming from the radiator overspill bottle

Mike C - yes the fan is working correctly - I will check for an airlock as you suggest

Then as Mike C and Z320 suggest, I will take the thermostat out and check.

Thanks for the suggestions - will report back when checked!

 

Stefan

 

[Z320]

How can there suddenly be air trapped, when the car worked well until one month before?

In my opinion „air trapped“ can only be the case when the engine has been drained and filled up with coolant again - with a not proper bleeding thermostat.

Then the coolant only rises in the radiator and not in the engine.

If your thermostat has no visible bleeding valve / drilling look at the valve / seat against a strong light

Edited December 26, 2022 by Z320

[John Morrison]

Hi Stephan

repeat a run to confirm car is good when being driven, and thus the rad is working 

but gets hot when tick over - water not circulating 

If electric fan has always been good then you are still looking at the water pump

Do you have correct antifreeze mix?

crunchyness could have start of freezing rather than loosened Crud

john

[Andy Moltu]

If the heater is working ok the water pump is probably functioning. It could be your thermostat has stuck closed.

[John McCormack]

8 hours ago, Andy Moltu said:

If the heater is working ok the water pump is probably functioning. It could be your thermostat has stuck closed.

Yep, I suspect the thermostat either stuck closed or sticking when opening.

Water pumps very rarely fail to pump, they often fail through leaking seals. I've never had an air lock in 55 years of British car driving and 47 years of TRs.

Worse case it could be a blown head gasket. My TR2 had these symptoms soon after I got it in the 70s, temperature suddenly shooting up to boil. Gasket was blown.

[Mike C]

4 minutes ago, John McCormack said:

Yep, I suspect the thermostat either stuck closed or sticking when opening.

Water pumps very rarely fail to pump, they often fail through leaking seals. I've never had an air lock in 55 years of British car driving and 47 years of TRs.

Worse case it could be a blown head gasket. My TR2 had these symptoms soon after I got it in the 70s, temperature suddenly shooting up to boil. Gasket was blown.

Thinking back 50 years, I found when a head gasket blew bubbles appeared in the radiator filler neck after I revved the engine- a simple test that can be done before pulling things apart.

[John McCormack]

6 hours ago, Mike C said:

Thinking back 50 years, I found when a head gasket blew bubbles appeared in the radiator filler neck after I revved the engine- a simple test that can be done before pulling things apart.

I've had a few head gasket failures. Symptoms vary. Usually, you can see gas in the coolant but not always and sometimes coolant loss is not obvious. 

In the case where the temperature rises very quickly you should see something.

I bought one of these coolant gas detectors. They work.

https://www.ebay.com.au/itm/385091638607?chn=ps&_ul=AU&_trkparms=ispr%3D1&amdata=enc%3A1kh20uMdjSK-IMcmrYbNNww37&norover=1&mkevt=1&mkrid=705-139619-5960-0&mkcid=2&mkscid=101&itemid=385091638607&targetid=1740279244689&device=c&mktype=pla&googleloc=9071814&poi=&campaignid=18277121424&mkgroupid=142426603833&rlsatarget=aud-1721181091144:pla-1740279244689&abcId=9301724&merchantid=591786250&gclid=CjwKCAiAqaWdBhAvEiwAGAQltpBRd5r7TF3w3TFEEIoO23AxqHTFGP4SIffcdaVG_bkYeYfVKsIjXxoCYbUQAvD_BwE

[Mike C]

51 minutes ago, John McCormack said:

I've had a few head gasket failures. Symptoms vary. Usually, you can see gas in the coolant but not always and sometimes coolant loss is not obvious. 

In the case where the temperature rises very quickly you should see something.

I bought one of these coolant gas detectors. They work.

https://www.ebay.com.au/itm/385091638607?chn=ps&_ul=AU&_trkparms=ispr%3D1&amdata=enc%3A1kh20uMdjSK-IMcmrYbNNww37&norover=1&mkevt=1&mkrid=705-139619-5960-0&mkcid=2&mkscid=101&itemid=385091638607&targetid=1740279244689&device=c&mktype=pla&googleloc=9071814&poi=&campaignid=18277121424&mkgroupid=142426603833&rlsatarget=aud-1721181091144:pla-1740279244689&abcId=9301724&merchantid=591786250&gclid=CjwKCAiAqaWdBhAvEiwAGAQltpBRd5r7TF3w3TFEEIoO23AxqHTFGP4SIffcdaVG_bkYeYfVKsIjXxoCYbUQAvD_BwE

That's a cheap way of confirming a cylinder head leak and better than trying to find and assess a bubble stream- the Repco equivalent tester was about 20 times as expensive.

[elclem1]

+1 thermostat easy to check and pennies to replace. That would be my first stop. Clem

[Ogrodz]

Hi Folks - Happy New Year!

I have now managed to properly investigate my overheating problem and thought I would update you with my findings.

In a nutshell, I believe the problem was an air lock caused by an empty heater box radiator. The valve to the heather box on the engine side was permanently turned off, so there was no flow of water around the heater box (maybe the heater box had been removed / drained for some reason by the previous owner). The heater switch in the car was not connected to the valve (explaining why no heat came into the car when I pulled the switch) . When I manually opened the valve, and took the car for a Christmas run, the water in the system redistributed as it flowed through and round the heater box effectively causing an air lock. When I stopped on the driveway after the run, despite the fan clicking in, it overheated. I assume whilst travelling there was enough cold air penetrating the engine bay to keep the temperature normal.

What is curious is I didn't notice any drop in coolant level in the radiator at first investigation - would the air lock manifest at the highest point - near the thermostat perhaps?

After leaving the car for a few days, the air lock must have worked its way round the system - such that when I checked the radiator next time the coolant level was way down. It took half a watering can to fill up the radiator!

Having refilled, started the engine with radiator cap off, massaged the large rubber pipes as the engine warmed to remove any further possible air locks and continually topping up with coolant, the car now runs perfectly again!! No overheating. On standing, the temperature rises as it should, the fan kicks in and keeps the temperature in the desired range.

So, Mike C - your hunch about an airlock was correct!

I took the precaution of purchasing a new thermostat, gasket etc.. from Rimmer Bros - so now I have a spare should the thermostat fail!

Anyway, hope this might help someone else with similar symptoms.

Stefan

 

[Mike C]

4 hours ago, Ogrodz said:

Hi Folks - Happy New Year!

I have now managed to properly investigate my overheating problem and thought I would update you with my findings.

In a nutshell, I believe the problem was an air lock caused by an empty heater box radiator. The valve to the heather box on the engine side was permanently turned off, so there was no flow of water around the heater box (maybe the heater box had been removed / drained for some reason by the previous owner). The heater switch in the car was not connected to the valve (explaining why no heat came into the car when I pulled the switch) . When I manually opened the valve, and took the car for a Christmas run, the water in the system redistributed as it flowed through and round the heater box effectively causing an air lock. When I stopped on the driveway after the run, despite the fan clicking in, it overheated. I assume whilst travelling there was enough cold air penetrating the engine bay to keep the temperature normal.

What is curious is I didn't notice any drop in coolant level in the radiator at first investigation - would the air lock manifest at the highest point - near the thermostat perhaps?

After leaving the car for a few days, the air lock must have worked its way round the system - such that when I checked the radiator next time the coolant level was way down. It took half a watering can to fill up the radiator!

Having refilled, started the engine with radiator cap off, massaged the large rubber pipes as the engine warmed to remove any further possible air locks and continually topping up with coolant, the car now runs perfectly again!! No overheating. On standing, the temperature rises as it should, the fan kicks in and keeps the temperature in the desired range.

So, Mike C - your hunch about an airlock was correct!

I took the precaution of purchasing a new thermostat, gasket etc.. from Rimmer Bros - so now I have a spare should the thermostat fail!

Anyway, hope this might help someone else with similar symptoms.

Stefan

 

Make sure your new thermostat has an air bleed hole.

[Z320]

I drained and refilled the cooling system of my TR4A (and other cars) several times without any attention on anything.

From detailed investigations how it works in my opinion an air lock is impossible and only a „I don’t know any other explanation“.

The air bleeding issue is only needed to top up the coolant, not to drive the car.

Ciao, Marco 

[matt george]

A good result!

[Steve-B]

Fantastic result and good knowledge sharing on your debugging the problem