rover v8 engined stag cooling

richardw · Post by **richardw** » Thu Jul 30, 2009 9:12 am

hi, chris the rad cap is 15 pound and i have always felt that the bottom hose has always seemed tp be quite hot.What does fwiw mean??You are right what you say about the pipes on the expansion tank,do you think its not plumb in correctly??The top hose never seems to getwater in until the stat opens.Would you say the stat housing wants changing for a different outlet-the top hose should be level with top of rad right??sorry for all these questions!!!Cant you just nip round,i'll make you a mug of tea!

I think i will need to get cooling pressure tested and take it fom there.How do you measure the pressure?Do you have any pictures of your system that might help........thanks again rich

CastleMGBV8 · Post by **CastleMGBV8** » Thu Jul 30, 2009 9:51 am

Richard,

I'm pretty sure your problem is an airlock caused by the height of the top hose which at it's highest point is quite a bit higher than the rad and air is being trapped in the hose.

This problem is being increased by the angle of the thermostat housing outlet which is pointing upwards and therefore increasing the height of the top hose.

If you could get a thermostat housing which points straight forward you could use an MGBV8 top hose which will then sit a lot lower, I am currently checking what thermostat housings can be used on the rover manifold and will come back to you.

Radiator condition could also be having some effect, if it's the original 35 year old rad it could be partially blocked and this is adding to the problem.

Once set up properly you need to get the front og the car as high as possible when filling the system and with the cap off expel as much air as possible.

Kevin.

Just found a thermostat housing with a horizontal outlet that should work with the rover manifold.

Dave Vale at V8 Conversions at Farnborough Kent 01689 858716 has them specially cast and has a couple, they are £22.00 + VAT and you can get the MGBV8 top hose from him as well.

If you have not done it, I would have the rad out and back flushed whilst your at it.

ChrisJC · Post by **ChrisJC** » Thu Jul 30, 2009 11:36 am

When I measured pressure, I used an oil pressure gauge (mechanical) on a long piece of fuel hose!

With my setup with expansion tank:

You can see in the top hose a 'thingy' which has a 15psi sealed cap. Any overpressure will come out along the small pipe into the expansion tank.
So the expansion tank is at atmospheric pressure. Then because this thingy is at the highest point, it automatically expels air, and draws in water as the temperature cycles.

I wonder if your setup won't automatically purge any air.

I made my thingy, but you can buy them. The important thing is that the cap has two seals, one at 15psi, and the other is always sealed.

FWIW is For What Its Worth.

Chris.

P.S. Don't drink tea!

richardw · Post by **richardw** » Thu Jul 30, 2009 9:21 pm

right guys quick update! went shopping with the missus &kids this afto,

collected season ticket for my mansfield town fc,

this chap was in mtfc car park handing out flyers for a mobile mechanic service he had just set up. Got talking and hes been round tonight tested the pressure & the readings on gauge were all over the place! He then took the expansion bottle of and tied it up half way up the bonnet, revved the nuts of the little v8 a few times-bubbles everywhere.Did this a few times till no more bubbles appeared.rechecked with pressure gauge on and this time it was rock steady......no nasties smells in the bubbles either-checked with the coloured water.Will now move expansion bottle somewhere higher to stop this in future.The garage that did the heads said the temp gauge was pretty accurate,this chap used his infra red jobbie and 90degree on stag gauge was 70degree on his infra red guage and after a hard run stag said 120 degree,infra red about 85 degree!!!!so after rad,pump,and heads replaced i am a bit pissed off/relieved .I now need a new temp gauge! what do you think of cappilary ones or should i stick with a leccy one? Just feel like i need to know the temp of my engine after all this effort. thanks everyone for taking the time out to help. Good to share a p[roblem eh? rich

RoverP6B · Post by **RoverP6B** » Thu Jul 30, 2009 9:41 pm

Hello Rich,

I am very pleased to hear that you are almost there. I know I do, and I am sure that I speak for all of us when I say we all like a happy ending..

As far as your existing gauge and sender go, try a new sender first and see how that goes.

All the best,
Ron.

topcatcustom · Post by **topcatcustom** » Fri Jul 31, 2009 7:46 am

Great news, though its a pity it cost you so much sorting out the wrong thing, we have all done it, I spent around £1000 replacing bits on the braking system on my lorry when I got it 'cos the brakes were hanging on when you took your foot off the pedal, eventually it turned out to be a crimped piece of nylon air hose that a 10pence connector sorted out..... that was painful

ChrisJC · Post by **ChrisJC** » Fri Jul 31, 2009 11:26 am

So it sounds like he's bled the system. I'd be a bit concerned that it could happen again because the expansion bottle is below the highest point on the system.

That's where a setup like I have comes in because it doesn't matter as long as the rad cap is at the top.

Chris.

gelmonkey · Post by **gelmonkey** » Fri Jul 31, 2009 12:04 pm

Hi Richard
Had similar problems with a V8 manta i put together for a friend some years ago.Remove top and bottom hoses and cap the bottom off.Put in two large spoons of bicarbonate of soda and then fill the rad with boiling water from a kettle and leave overnight.The bi carb fizzes and clears out any crud.Drain and refill in the morning.Disconnect the highest heater hose and fit a gartden hose to the pipe and blast it through the whole system.Refit heater hose start engine.You can fit a bleed valve from a vw polo/golf and run the engine with the valve open ,this will erradicate any airlocks in the system.
This may well solve your problem
Dont go with the liners are moving theory cause 'that dog don't hunt'
Also, you could as already suggested, go for an ali rad.Summit racing in the states can do one for about $80 and they work fine.Look at Muscle Manta pics to see what you get.Brise fabrications could also make you a bespoke unit or you could try Serck Marston.Hope this info helps
Paul

richardw · Post by **richardw** » Fri Jul 31, 2009 9:09 pm

I am going to move the expansion tank up on bulkhead as soon as i can,already had the hose on heater matrix and the radiator has been recored about a year ago.Does anyone have experiance with cappilary temp gauges as i was going to fit one of these,are they more accurate or should i stick with a sensor job.If so weres best to get one from (new) cheers rich

mgbv8 · Post by **mgbv8** » Fri Jul 31, 2009 10:02 pm

It should not matter too much where the exp tank is mounted. As long as the hose from the cooling system to the exp tank is as high as possible. And the connection to the exp tank is connected to a dip tube in the tank. And the exp tank has water at least half way up the dip tube. Or that the exp connection is at the bottom of the exp tank from the engine. And the tank has some water in it.

Any air collecting at the high point should be forced into the exp tank as the system gets pressure. This will be replaced with water from the exp tank when the system cools. But you need to make sure that you check the exp tank level when cool and top up as required.

But in the real world, air in the system often gets entrained in the water flow and bypasses the connection to the exp tank. So its better to fill the system slowly and release the air from the highest point from the start.

Or, if you are happy that you can vent most of the air out of the system while cold filling (which should be easy) the exp tank is just an exp tank. As long as it has water below the dip tube, it should not matter how high or low it is!!

richardw · Post by **richardw** » Mon Aug 03, 2009 8:33 pm

final update..................fitted expansion tank up higher near bulkhead,cleared all air out of system.Then i fitted another temp gauge that had been lying about in garage ,allready tried one b4 about 6 months ago that gave same readings as origanol one.But i thought iwould just try another one! I let car warm up took it for a drive 80 degree,gave it some real stick :racing

for the first time in about a year-80 degrees!drove it steady-80 degrees,could not beleive it a-faulty gauge£800 quid later and all down to a faulty gauge,well two really whats the chances of that, idont think its ever been overheating..................Came home left it ticking over on drive,temp rose up to 90 degrees switched fan on and it came back down again-fantastic eh! i can now enjoy this car for whats left of the 'summer'. thanks again for all your views. richard

mgbv8 · Post by **mgbv8** » Mon Aug 03, 2009 8:39 pm

Good result eh??

Enjoy driving that thing mate

jefferybond · Post by **jefferybond** » Tue Oct 06, 2009 12:11 pm

RoverP6B wrote:Hello Rich,

Not using a thermostat could well be a large part of the problem!

As the thermostat slows the coolant leaving the engine, the coolant is able to absorb heat out of the engine and then transport that heat to the radiator for removal, but without one the coolant does not work any where near as efficiently, leaving most of the heat still in the engine!

Ron.

I believe that is a myth! No stat will mean that the water flows faster, and that will mean that the heat absorbed by *each litre* of water is less, but the increased flow rate more than makes up for it.

In fact, a faster flow rate will mean a more even temperature across the block and heads, and can't be a bad thing.

Jeff