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

[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

[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!

[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

[tom_609]

We had big compression variation initially on one side. This all became even following head gasket replacement on that side only.

Dollyman1850 said:

Is the header pressurising after a short time on the drive??

I'm not quite sure what you mean? My ignorance more than anything! Water pressure or cylinder compression?

V6Pushfit said:

Also heater hoses - are they looped over in a way to cause an air lock and lack of circulation.

Water seems to be flowing fine throughout entire system. Heater hoses are getting hot with rest of system so doesn't appear to show the symptoms of an airlock.

plasticpig72 said:

When you have found and fitted the replacement inlet manifold you could check mixture with a ColorTune plug. For the helicoils they need a very small chamfer at the top of tapped hole before fitting. Then fitted a 1/4 of turn down from surface. Don't use Loctite on Helicoils.
Imho the crack in the inlet manifold would make a very lean mixture and high temps.
Alan

We have a new inlet on the way so no need to worry about the helicoils. Hopefully this one has original threads that have not been destroyed! The cracked inlet is only a new development and the car was overheating long before this. It was only on wednesday that the inlet gave up and the damage is not in a place that would affect mixture. Once we get the new manfifold on we can try to tackle the overheating issue again.

chassyman said:

i absolutely agree with neil. when you changed your head gasket did you have the head crack tested if it overheated prior, and did you get the head skimmed? you mention a stream of bubbles visible in the water flow, that in itself is the most significant observation, look deeper!!!! best regards and luck keith

We haven't had the heads crack tested and only removed one side to sort the head gasket for the low compression cylinders. Head has not been skimmed. The stream of bubbles from the swirl-pot we assumed was the system working the air out still from when we flushed the system. Is there an easy way to check for head issues without taking the engine to bits. We will if we have to but don't want to go down that route before we've tried all other easier options.

[tom_609]

plasticpig72 said:

I've just removed the Core Plugs on the outside of the Block on my 3000M because one was leaking.
That's 2 each side and cannot believe the amount of crap, sludge, debris inside Waterways.
If you recore Rad and some of this debris moves it could easily block your nice new recored Rad.
Before i fit the new Core Plugs i will flush out the Waterways. The most debris is next to n°4 Cylinder.
For sure this will not help the cooling with lots of debris. Imho without removing the Core Plugs it's impossible to flush correctly.
Alan

Thanks for all your help so far. I bought a new set of core plugs from Burton Power, Ilford this week. For now I have just flushed system to get any loose bits out. A little bit more crap from the block came out but nothing significant.

We are going to put everything back together with the re-cored radiator and if it is still overheating then the only thing left to do is remove and check the heads again and do head gaskets again. Saying this it will probably make sense at this point to remove the engine completely and strip it down and do the core plugs at the same time. I would have liked to do core plugs now but there is no way I can remove (let alone replace) any of them whilst the engines fitted

[tom_609]

Dollyman1850 said:

Last time you did your heads did you re-use your head bolts?

Its a common engine building mistake when changing gaskets not to ensure that your head can clamp down. I have known and seen many times a combination of stretched bolts and thinner replacement gaskets be the cause of a head which pulls down but bottoms out on the thread… You can measure this but an alternative (cheap) method of ensuring you are not bottoming out is to take a couple of mm from the bolt end . Also make sure your thread holes are cleaned out

N.

Yes we did re-use the head bolts, we only replaced the head gasket on one head which had weak compression on 2 of the cylinders. We did a second compression test after changing the head gasket and all seemed fine so definitely clamping correctly and we re-torqued the head bolts after driving a few miles. Gasket looked like it was a like-for-like replacement and we cleaned both the bolts and threads before reassembly.

Thank you for the advice nonetheless, worth considering for future engine work

[tom_609]

Update for all

Just collected re-cored radiator. I've had it done with standard 4-core crossflow setup but instead of curved fins (6 fins per inch) we have gone for straight fin cores with 12 fins per inch. This is supposed to dramatically increase cooling as the surface area of the fins is effectively doubled, helping with heat dissipation. Adrian also recommended having a 22mm fan switch boss installed which we have had done. Very happy with the results!




Upon collecting the rad we were shown the original core. Approximately 1/3rd of all channels were blocked at one end and many of the remaining water channels that look clear from the pic were actually blocked at the other end or in the middle of the channel. A flow test showed that the radiator was not able to get water out at the same rate it was taking it in. The shop reckons it is highly likely the rad was the source of the overheating problems but even if it doesn't fix it, this will definitely help and would've needed doing very soon anyway.

I cannot recommend the work of Commercial Specialists in Luton enough. They are 2 guys in a small radiator shop who have produced rads for Aston Martin and been going since 1982. Happy to discuss your needs in length and the moment I mentioned the TVR he knew the dimensions off hand! Was very impressed and over the moon with the quality of their work



Just got to wait for the inlet manifold to turn up and I'll put the cooling system back together and see where we are at!

[tom_609]

Update on events

replacement Inlet manifold turned up. An attachment on the new manifold wasn't required but when we tried to remove it the metal snapped clean in two due to corroded threads. We managed to cut out the metal left inside the thread and re-tap it so that is all good now.

Yesterday we also noticed the carburettor spacer had completely disintegrated and also been bodged by a previous owner. Managed to source a replacement from a guy around the corner and picked it up early afternoon today.

Got home from work and switched the inlet manifolds over using new gaskets all round, connected up all the hoses, flushed the system once more, rewired the messy wiring to the new radiator and our new fan switch and topped up with water.

We started the car and topped up the water whilst air in the system was 'burped' out. After 10 mins we thought the fans weren't wired up correctly but to our joy the car just wasn't hot enough yet! We then felt the thermostat open and 5-10 minutes after that the fan kicked in. The car is maintaining a good and stable temperature Been out for the longest drive in my ownership and no overheating whatsoever! Temperature cools nicely as the speed increases and sits perfectly in traffic even with 1 fan (we have a second fan wired to an override switch just in case).

After a year of ownership we have finally sorted this frustrating issue. I believe it to be mainly the recored radiator however everything else will have certainly contributed too: installing an 82 thermostat (no thermostat before at all), new water pump, system flushed. I've bought a bottle of water wetter which should give me a couple more degrees flexibility too. Also need to drain some water and top up with actual coolant/antifreeze as the winter will be here soon and to save my precious new rad cores Just time to sort out my very temperamental throttle cable now which slips and takes away all pedal control with it. That's for a different thread though I reckon

We are overly grateful to all of your help and if I ever meet any of you I owe you a pint Finally got there!!!

[tom_609]

V6Pushfit said:

Bloody good news got there in the end. You did today's work pretty quick too!

Yep, got home from work early and managed to go collect the spacer then it was solid work from 3-7pm. It was more putting everything back together more than anything but as we all know "I've just got to switch that for that" is never a simple job haha

TVRMs said:

Hop that's the problem sorted

I hope so too