Water Temps

[DHGTR]

Ok guys

Take me back to basics, do any of you have a 'technique' for filling the engine coolant.

Went for an easy 2mile drive folowed by 10 mins on tickover with rad fan override switched on, the coolant decided to empty itself over the drive through the expansion tank pipe. coolant in car was water/water wetter/antifreeze mixture.
temp gauge was reading well over 250f (110c).
Heater matrix not open.

Any ideas - guessing some kind of airlock but take it from basics.

Dave

[60mph]

I take it the fans were running ?
I had air locks in mine but mainly in the heater pipes and matrix .
Do you think your engine thermostat is opening ? Take it out and try again with the heater open .
Most upsetting ; mine overheated because the fans cut in and out a few times so I assumed all was well but then the relay fuse blew without telling me . I have one relay/fuse for each fan now . Funnily enough I am just fitting an overide switch now so I can turn the fans on if I panic .

Can only be your thermostat , can't it ?

Frank/Stourbridge

[738 driver]

Depends.....was it empty or just low to start with and if empty, was that routine service stuff or a problem?
Heater is best left in fully hot position prior to filling/cold start... so you dont create any minor initial air-locks...(might prevent flow)
Once filled to header tank level start engine and just allow to tickover till the stat opens, continue to top-up the system (very slowly if using cold mix). You should see flow through the header tank and also any air escaping.
Personally I dont rev an engine at all when doing a coolant bleed, nor fit the header/filler cap until I can see good solid water flow in the return.
Sounds like your motor got too hot, too quick and took a large gulp of air as well.
Let it cool fully before putting cold fluids back into it. I would think thats particularly important if you are running an older 400 SBC block. Apparently they are notoriously thin around the bores.
Good luck,

Dave.

Edited, Sorry Dave I misunderstood your post, thought you were trying to do a coolant bleed and took it for a run to warm up with a resulting boil-over.
In any event I'd still bleed as described above.

Edited by 738 driver on Friday 10th April 17:58

[60mph]

p.s. I thought you drove it to and from the SVA ? If it was O.K. then something must have changed .

Frank

[DHGTR]

Hi Frank

Fans were running and thermostat working (jug of water test)
I noticed that temp went way up on way back from test but because there was no spluttering or spittin i put it down to faulty temp sensor. I have mine in thermostat housing, is this where averyone else has theirs.
First time ive had ample time to play since the sva. really p.....d off at mo though.

Dave

Edited by DHGTR on Friday 10th April 18:08

[ROWDYRENAULT]

I have had mid engined cars for awhile they are not easy to burp. here goes, lift the back of the car as high as is prudent. fill the system with the heater valve open. Start the car with the cap off and let it run for a minute, install the raditor cap, cycle the motor up to 3000 rpm at about 50 second intervals until the engine reachs operating temp the fans are on and the thermostat are fully open.shut the engine off, remove the cap. Leave the cap off start the engine and let it idle for a minute. shut the engine off Refill the surge tank. repeat the process back to full operating temp again, refill and you should be done. On the ls motors you should see a steady return from the head bleeds back to the main water tank when the system is completly full. These instructions are based on the Renault R5 Turbo book and the Hypertech instructions that came with the lower temp thermostat that I use in my ls1. The R5 is a pain to burp but once done correctly it will never overheat. The gent that drove his car without a problem and then had an issue, that is classic in mid engine cars with a air pockett in the system. once the air gets to the pump and it then cavatites the car will overheat and if you put your hand on the raditor it will only be warm at best. thats when you know you either have a stuck thermostat or an air bubble. Lee

[V8Dom]

DHGTR said:

Ok guys

Take me back to basics, do any of you have a 'technique' for filling the engine coolant.

Went for an easy 2mile drive folowed by 10 mins on tickover with rad fan override switched on, the coolant decided to empty itself over the drive through the expansion tank pipe. coolant in car was water/water wetter/antifreeze mixture.
temp gauge was reading well over 250f (110c).
Heater matrix not open.

Any ideas - guessing some kind of airlock but take it from basics.

Dave

i have a snap on devise that sucks all the air out of the system and draws coolant back in again... Its great....... i work at Yoxal during the week if you want to come and borrow it

Dom

[Steve_D]

I have never had an air lock with mine in 5 years.
When you fill you must have the heater on so water can circulate through there.
When you finish the swirl pot should be full to the brim and the expansion tank no more than 1/3rd full when cold.

Have you photos of where the pots are fitted because the height is important.

Steve

[ROWDYRENAULT]

Steve D has a great point the tanks should be mounted higher then the engine so that any air tends to go towards the tanks. The reason that IO have allways done this with the tail up is to make sure the place that you are bleeding the air from is the highest point in the system, a problem on the Renault. Lee

[DHGTR]

The top of my rad pot (lhs when looked at from rear) is level with top of stat housing, , so the water level is almost level coming across the pipe. could the tank do with being raised a slight bit?

[Steve_D]

DHGTR said:

The top of my rad pot (lhs when looked at from rear) is level with top of stat housing,...

My pots are slightly higher than that but not much.

Steve

[DHGTR]

right, back out and refill the water this morning. nice and calm.

Thanks guys

[60mph]

Hi Dave

I think if you fill the system slowly with the engine running you should get rid of air locks which are definately the cause . When my engine was up to temp' I reved it up by hand to spin the water pump up and a load of air came out . You are filling the nearside pot , aren't you ? RR makes a very good point ; nose downhill especially with the diameter of those horizontal pod pipes . I'll come over if you get stuck .

Frank

[60mph]

P.S. temp sensor in side of block under nearside exhaust manifold ; but this would not cause your problem I don't think .

Frank

[738 driver]

If you tilt the car nose down, would you not run the risk of trapping air at the rear of the block/heads, as the header/filler tank would then be lower?
I'd just keep the car level, loosen the header tank and hold it as high as the hoses will allow whilst you fill/bleed.

[60mph]

Yes but a shallow angle would get those side pipes out of their horizontal position .

Frank

[bluesatin]

Obvious question but do you have the correct cap on the swirl pot/ expansion tank?

[DHGTR]

Hi Guy

I have the sprung cap on the offside expansion tank and the fixed cap on the nearside swirl pot. yes no ??

[Steve_D]

DHGTR said:

Hi Guy

I have the sprung cap on the offside expansion tank and the fixed cap on the nearside swirl pot. yes no ??

Correct.

Steve

[bluesatin]

I had the same problem with mine soon after I completed the car. The car was over heating etc. I found the problem to be the expansion tank cap not turning all the way round- this led to no pressure in the system!