overheating roadblock 3000m

[tom_609]

Hi all,

This is my first post after doing searches for overheating issues and trying everything i had seen suggested on other threads.

My 3000m overheats after running for about 15mins. We were initially getting water spraying out the swirl pot but after realising it could go tighter the pressure was then correctly being dispersed from the pressure cap of the expansion tank.

- The car is not leaking coolant
- Compression test showed low in one cyclinder, changed head gasket and compression now fine
- Currently running without a thermostat so it not opening is not the issue
- Checked timing with a strobe
- top and bottom radiator hoses are getting warm as expected
- Water seems to be flowing throughout the engine and cooling system fine
- Have the twin electric fan setup pulling air through the radiator
- Have replaced the waterpump (old one seemed fine anyway)
- HT leads and spark plugs all replaced
- Tried driving at a steady speed to get air flow over the engine but same issue

I'm racking my brains and really starting to get annoying now, any ideas are much appreciated and thank you in advance!

Tom

[RikJonAtk]

How crusty is the radiator its self?

Are the fans shifting air in the correct direction?

Is it bled properly?

[Astacus]

Hi welcome to the forum. There is a lot of expertise here so there will be someone who knows the answer no doubt. A few possibilities occurred to me.

If the car was restored before you bought it, are the hoses correctly connected? Sounds dumb but I have heard of this happening!
You say that coolant is correctly circulating, but maybe there is an airlock. I think in some M series cars it's easy to get airlock , even after you are sure there aren't any!!.
Also, maybe there is sludge in the system. Have you given it a flush through?

[GAjon]

Have you verified the gauge is correct?
Check flow through the heater matrix, they can air lock there.

[Cerberus90]

GAjon said:

Have you verified the gauge is correct?
Check flow through the heater matrix, they can air lock there.

+1 on checking the gauge/sender. A cheap IR temperature gun can be very handy in this sort of situation.


I'd also get a thermostat back in, as it can sometimes do more bad than good when running without one (messing with the flow of the water out of the block creating hotspots).

[plasticpig72]

maybe put thermostat with a small hole drilled in it and also check if there is a restricter inside heater hose to divert water through rad. Has the new waterpump you fitted got a cast impeller that pumps correctly. The cap on the swirlpot should just be a blank cap and not a rad cap.
Alan

[chris52]

plasticpig72 said:

maybe put thermostat with a small hole drilled in it and also check if there is a restricter inside heater hose to divert water through rad. Has the new waterpump you fitted got a cast impeller that pumps correctly. The cap on the swirlpot should just be a blank cap and not a rad cap.
Alan

The cast / pressed impeller is a good idea the pressed ones are cr@p. But not all the cars had an expansion tank after the swirl pot the early ones just had a overflow tank so the cap on theses were a rad type cap not just the blank cap.

Chris

[plasticpig72]

If the swirlpot has a rad cap check to see where the small bled from top of rad is connected to.
Alan

[tom_609]

Wow didn't expect such a quick response, thank you! Time to work out how to reply to each without doing separate posts, here goes...

RikJonAtk said:

How crusty is the radiator its self?

Are the fans shifting air in the correct direction?

Is it bled properly?

Radiator itself looks brand new and believe it was replaced during the restoration by previous owner.

I did wonder about fans but they are mounted behind the radiator and definitely pulling air through as I can feel it and see the direction of rotation is correct on both

How would I go about bleeding the system? I have run the engine with the swirl pot cap off and watched the level rise and drop and bubbles coming out; I have emptied the coolant completely and refilled twice trying to find a fix so assumed that was the air working its way out.

Astacus said:

Hi welcome to the forum. There is a lot of expertise here so there will be someone who knows the answer no doubt. A few possibilities occurred to me.

If the car was restored before you bought it, are the hoses correctly connected? Sounds dumb but I have heard of this happening!
You say that coolant is correctly circulating, but maybe there is an airlock. I think in some M series cars it's easy to get airlock , even after you are sure there aren't any!!.
Also, maybe there is sludge in the system. Have you given it a flush through?

Many thanks for the welcome, I seem to have come to the right place!

I thought this but found a 3000m cooling diagram and mine seems to be plumbed up correctly.

I ran the car until it overheated recently after flushing and replacing the coolant and lots of air was working it's way out the swirlpot. The air escaping as bubbles did not stop however. Before refilling the system i ran water through the cooling system and all seemed clean. When I initially drained the system everything that came out was immaculately clean.

GAjon said:

Have you verified the gauge is correct?
Check flow through the heater matrix, they can air lock there.

As in the dashboard temp gauge? I have not but regardless it starts to physically overheat at the same time as the gauge getting towards boiling point.

How would I go about checking heater matrix flow/clearing an airlock? I don't have a bleed valve where I believe some have them fitted. May be a worthwhile investment.

Cerberus90 said:

+1 on checking the gauge/sender. A cheap IR temperature gun can be very handy in this sort of situation.


I'd also get a thermostat back in, as it can sometimes do more bad than good when running without one (messing with the flow of the water out of the block creating hotspots).

I purchased an 82 thermostat from Burton Power recently so will get it fitted. I only recently got round to tackling the overheating issues recently and realised the previous owner never actually had one fitted

plasticpig72 said:

maybe put thermostat with a small hole drilled in it and also check if there is a restricter inside heater hose to divert water through rad. Has the new waterpump you fitted got a cast impeller that pumps correctly. The cap on the swirlpot should just be a blank cap and not a rad cap.
Alan

I will get the thermostat fitted and drill the hole too as I've heard it helps. Will check to see about the restrictor. I'm not sure about the impellor, if it helps I purchased the waterpump from burton power: http://www.burtonpower.com/water-pump-ford-essex-v...

Yes I have a blanking cap on the swirlpot and a 13psi cap (off the top of my head) on the expansion tank

[Englishman]

Not on a 3000M, but one TVR I bought had the heater control valve (3 hoses) fitted the wrong way around. The result was when the heater control was set to hot eveything was open and fine, but when closed it was stopping circulation back to the engine (rather than to the heater matrix) and causing overheating. Just a thought.

[anonymous-user]

You sure you've sorted the head gaskets?

[plasticpig72]

to be sure there is no airlock in the heater in the past i have slipped a heater hose of at a high point to bleed. That is with caps in place and engine running.
I also removed rad and also heater matrixs then flushed out using garden hose
Alan

[ausi steve]

I live in Perth West Australia, a very hot climate.
I bought the 3000m out of the UK in 2010 and have experienced it getting too hot.
I bought a product "Liquid intelligence" from Sydney [try googling their website for details, but I'm sure their is a UK product that does the same]that removes all crap in the engine block, it brings it back to the cast iron as well as cleaning the radiator.
It was explained to me that over time, calcium builds up in the engine and as calcium is a good insulator it inhibits the flow of heat from the engine to the water coolant.
I also fitted a new thermostat, you should always have a thermostat as without it the water flows too quickly through the radiator for much cooling to take place.
The combined clean engine cooling system combined with the new thermostat fixed the problem.
As my car has the small radiator & the electric fans fitted to it work good there was a problem when stuck in traffic on hot days so I removed the spare tire & fitted a 12 inch electric fan in front of the engine to allow air to be circulated around the engine & get rid of the heat that was being pushed there by the radiator fans. I only switch it on whilst stationary from a switch by the steering column.
I can now use the car all year without overheating problems.
Hope this may help.

[ivanhoew]

Tom , does it overheat in all situations ? eg sitting still ticking over as well as when driving .,does the speed your driving at affect the time it takes to boil over ?

Two things that made a big difference to my car ,turbocharged 3.5 litre v8 ,were

a) Fitting fans from another car that had the full plastic shroud around them , they just fitted side by side on the back of the tvr rad ,and made a big difference in traffic and sitting still.

b) Fitting a air dam anywhere air could get around the rad ,on the stock car this is done by the spare wheel and the wheel arches ,but if you can identify any areas that are still open and block them this helps a lot at higher speeds .

one last thing on my car a rad cap had been fitted with the wrong length .this meant that the system was not pressurising at all because the spring loaded cap centre was not sealing .


regards
robert

[Andrew Gray]

[tom_609]

Sorry for slow response guys, haven't had much opportunity to work on the car recently! Plan today is as follows:

- Install an 82 thermostat which I have drilled a small hole through
- Check heater control valve fitment
- Try to bleed system by removing hight point heater hose with engine running and caps on
- Will look into the liquid intelligence UK equivalent to clean out potential crap from inside the block

If all this fails I will remove the radiator and look into having it recored (I believe I can have this rebuilt with 7 cores). Need to get quotes first.

For reference, the car overheats when idling on the driveway, being driven from startup at slow speeds and high speeds. No change in driving affects it, the car overheats every time. I have the twin fan setup with plastic shrouds. one cuts in at certain temperature and the second I can manually turn on/off with an over-ride switch on dash panel. Both fans are mounted behind radiator (pulling air through) and are definitely moving air the correct way.

Thanks for all your help, it is all appreciated!

[ivanhoew]

tom , something else that can chronic overheating is a stuck advance mechanism in the distributor . if the timing is not advancing , and stuck at 10 degrees or whatever ,then the engine gets v hot .may be worth getting a timing light on it and revving it up to see if the advance it working .

[plasticpig72]

In your list i don't see plugs mentioned, are they a nice colour and not running with a lean mixture. What grade plugs have you fitted
Alan

[Hansoplast]

Beste Tom,
What I miss in your list is; to lean petrol
That wa the problem with my overheated Triumph TR3.

Good luck.
Hans

tom_609 said:

Hi all,

This is my first post after doing searches for overheating issues and trying everything i had seen suggested on other threads.

My 3000m overheats after running for about 15mins. We were initially getting water spraying out the swirl pot but after realising it could go tighter the pressure was then correctly being dispersed from the pressure cap of the expansion tank.

- The car is not leaking coolant
- Compression test showed low in one cyclinder, changed head gasket and compression now fine
- Currently running without a thermostat so it not opening is not the issue
- Checked timing with a strobe
- top and bottom radiator hoses are getting warm as expected
- Water seems to be flowing throughout the engine and cooling system fine
- Have the twin electric fan setup pulling air through the radiator
- Have replaced the waterpump (old one seemed fine anyway)
- HT leads and spark plugs all replaced
- Tried driving at a steady speed to get air flow over the engine but same issue

I'm racking my brains and really starting to get annoying now, any ideas are much appreciated and thank you in advance!

Tom

[tom_609]

Hi guys, got the 82 thermostat (with small drilled hole) in the car, tested it and realised the thermostat housing was leaking. Closer inspection shows that a previous owner had stripped the inlet manifold threads and installed threaded inserts. These were installed too close to the edge of the inlet casting and has actually cracked the inlet. So before I can tackle anything I've got to get a replacement inlet sorted.

- The plugs were checked and replaced less than 100 miles ago and all seemed good
- Once the replacement inlet is sorted we will run the car to check how things have changed since thermostat install.
- If it's still getting hot we will look at the timing advance and air/fuel mixtures (it has been spluttering on full acceleration the last few times it ran so could be too lean in the higher revs)

Thank you guys, will keep you posted, All the help means the world