Overheating

Gents,
New issue this week,after 10 miles temp gauge goes over halfway, checked engine both large diameter hoses and expansion tank are really hot. Considering draining system and using Radflush, apart from the bleed valves is there a main drain plug somewhere that should be used?

I am a where that the GTA can have water pump issues but wanted to do the obvious cheap checks first i.e should I be sourcing a replacement thermostat.

Many thanks for your previous advice

Normal running temp should be up to the single tick line on the gauge - slightly to the right of vertical.

If you're properly running hot then most likely causes will be the rad being blocked / gunked up or the thermostat - the pump is rarely a problem.

Regarding flushing the system, undo the main hose at the front and let it drain out that way. You can then put a hosepipe in the expansion tank and let that run through and backflush the rad as much as you can.

Use the type D coolant (from Renault) when you do refill, but you might want to stick to normal stuff for a few weeks until you're sure you've cured it and want to invest in the Type D. It's not actually that much more expensive anyway, but it's pre-mixed, hence you might not want to waste it. But it really is the only stuff to use.

There's a drain hose on the rad (half way up) that's often blocked, (use an old bit of wire and it will unblock) and apart from that the best approach with refilling is to park the car with its nose down-slope as it encourages the system to run through and you can bleed it better. You'll never bleed a GTA system perfectly the first time out so you usually see the water level drop after a day anyway as all the bubbles run through.

If you're draining it down I'd start with this and at the same time swap the thermostat as it's a 20 min job to do that while the system's empty. If you then test it again and are still seeing the same results then I'd be looking at the rad perhaps being properly blocked and needing replacement.

Headgaskets can cause overheating, but they're pretty tough really - it's rarely the case and should be your last resort anyway.

........apart from the bleed valves is there a main drain plug somewhere that should be used?

Hi. The first question is .... Have you checked if the rad fan is coming on ?
There are two drain bungs, one either side of the block, and I favour removing the rad fan switch close to the bottom of the rad , off side, to get rid of most of the rest of the coolant.
It might be worth checking the thermostat by removing it and seeing if it opens when put into boiling water. If it works, then it will make refilling easier to drill a 2.5mm hole in the thermostats highest point if it is not fitted with a jiggle valve.
Be sure when refilling that you raise the back of the car up to allow the air to escape to the rear of the car from the horizontal pipes under the floor. Fill slowly to allow the air in the block to escape through the small hole in the thermostat ..... and be sure to refill with Type D coolant from Renault.
Hope this helps.

Good points John. I'd assumed the rad fan was working but 'assumption is the mother of all f ups' to quote Under Siege 2.

Re the thermostat. Watch out with the testing in boiling water unless you have another to check it against. I had one that would open but was slow and wasn't opening fully.... tested against a new one you could see a marked difference, but on its own you would have assumed it was working how it should.

[johnb]

Certainly worth checking if the radiator fan is cycling on and off as John suggests.
I've just had that problem on my A310V6 where the fans weren't coming on at all. What I found was that the plastic part at the back of the switch, that holds the two terminals, was loose and could rotate. I prised this out and found the two wires inside had sheared so no wonder it didn't work. I've fitted a new one from Mecaparts and it now works as it should.

As I work with this stuff everyday word of advice regarding the use of the current Renault coolant,
It is best to not to mix with regular tap water that can be left after a flush as the minerals in tap water can react when heated in the mix.
This is why the Renault pre mix stuff is made using demineralised water.
I can find the pre fill liquid part number when I get back to work on Wednesday if requires.

Thanks Guys,
Comments are most helpful and give me the assurance to continue with the gremlins rather than leave the car with one of the specialists as I get a sense of satisfaction in a successful self repair. I did forget to mention that both fans do come on fairly regularly.

If I may ask another really tricky one, the car accelerates really well and is happy at higher speeds but coming down in speed through the box especially into second at roundabouts the engine is lumpy and holding back this gives very jerky gearchanges, and going through roundabouts it feels as though I am in too higher gear and in urban driving I am starting to ride the clutch or give to many revs. I know that the previous owner replaced plugs,plug leads, and distributor cap, I have checked the timing which is set on the wide marker, I assumed the two to the right were for 5 and 10 degrees respectively. CO levels seems low but gas analyzer is very old and tail pipes black.

With 126000 miles on the clock would I be best to bite the bullet and go down the replacement Holley road or try and keep the old carbs and have them set up by a GTA specialist or have I missed some simple adjustments.
Any thoughts would be helpful.

................ I did forget to mention that both fans do come on fairly regularly.

You say .... "Both Fans", the Atmo's usually only have one fan, are you saying that your Alp has two radiator fans, or are you referring to the engine compartment cooling blower/fan as one of them...... note that they are individually switched.
Also, regarding the quote above, Is/are the rad fan/s running when the " temp gauge goes over halfway" ?
With regard to your "coming down through the box" problem ........ could it be due to a higher than normal idle speed, which should be around 850 RPM when the engine is hot.. There is a condition that if not working properly, will cause the idle to not fall below 1100 RPM.
Final question, do you have a service manual which includes the operation and set up of your carburettors ?

Thanks John C,
Looks like I have another issue, no warning lights when the fans come on, I will need to do a static test to check when the rad fan comes on and engine compartment fan. When parked up the rad fan switches off first then the engine compartment fan. Would I be right in assuming the advice on antifreeze is that I could source from any Renault dealer but for a thermostat go to a specialist such as ART.

The car came with a photo copied workshop manual plus a highly detailed separate carb testing supplement which is very complex to follow.
The workshop manual I am O.K with in terms of following the idle screw adjustment and mixture screw which I am reluctant to touch.
Hot idle revs seem to average at 1000rpm.

Regards

Looks like I have another issue, no warning lights when the fans come on,

On the Atmo, there are no warning lights that come on when the fans operate.

When parked up the rad fan switches off first then the engine compartment fan.

Yes, that's right. The engine compartment fan can run for quite a long time after the engine is switched off ...... sometimes 15 mins or so. The rad fan will stop when you switch off the ign.

Would I be right in assuming the advice on antifreeze is that I could source from any Renault dealer but for a thermostat go to a specialist such as ART.

Yes,... Type D coolant should be available at all Renault dealers .... if they have not got it, they can order it. Just make sure you get it.
With regard to the thermostat, Renault only now supply the 610 thermostat (86 degree ...... GTA ones are 88 degree) Simon Auto's do the 88 degree ones. It is up to you which one you choose .... I don't think it makes too much difference.

The car came with a photo copied workshop manual plus a highly detailed separate carb testing supplement which is very complex to follow.

Your idle revs seem to be a bit high for my liking, I suggest you read up the section on "Accelerated Idle". as it might be that is where your idle revs are being held up. Come back to me if there is anything that wants clarification.

The workshop manual I am O.K with in terms of following the idle screw adjustment and mixture screw which I am reluctant to touch.

I would not touch either of these until you have checked the above and confirmed that the Accelerated Idle function is working.
I hope this helps.

P.S. ............. you might also like to check the operation of the automatic choke. With the top cover of the Air Filter removed, with a cold engine, the choke flap in the single carb should be closed. On starting the engine, it partly opens, then when the engine is hot, it should be fully open (vertical).

[John Sweet]

With regard to 2 fans, the atmo s with air conditioning came with 2 fans on the radiator to make up for the fact the air has to go through the air con rad first. This makes the normal rad less effective. The best way to clear the bleed tube on the radiator is to use WD40 with the tube connected - spray a little and then push it through a little. Much more gentle than wire. If you get the engine warm enough to pressure the system this helps (but wear rubber gloves for when the hot water appears and you are trying to get the bung back in). Depending on the car the temperature gauge can go a little above the norm before the fans cut in and the water circulates to lower the temp, especially if you hit a traffic queue after a fast run. Radiators do fill up with craps at the bottom which is hard to clear without taking it off. But if you get that far you might as well replace it.