I'm so pleased people here are saving time and lots of money by adopting my mod. In the original mod., the slightly imprecise fitting of the modified thermostat was enough to release any trapped air. It's not a great worry as the coolant pump will force the air out into the header tank anyhow. Also some air will be dissolved into the coolant. This was one of my reasons not to remove the coolant much below the level of the job by using a cheap caravan plastic water pump to get it out.
As has been said, a VERY small hole may be drilled in the actuator plate to substitute for the jiggle-pin system as in most thermostats.
Now you can spend all that money saved on diesel!

Leedsman.

 

Hi there all

Well searching through my tools i find i didn't have any drills that size so ive removed the thermostat and put it away for time being until i get the right size drill. I found while the stat was in place the top hose was hot the engine end and cool the radiator end, it stayed that way even when the engine was up to temp, i presumed that it was because there was no small hole and i did purge the system well too. So ive removed it to prevent any engine overheating and damage problems but ill have another go when i can get the hole drilled

Pete......

 

when I first did mine I didn't drill a hole. It warmed up very quickly, and I went on a 200mile trip.... with the heater on hot it stayed at around half way on the gauge, as soon as I turned the heater on cold the engine temp warmed up towards the red zone. I stopped and could feel that the engine side hose was red hot and the rad side hose, downstream from the stat was cold. The rad cooling fans were also running flat out, but of course not doing anything as the stat was closed due to air locking.

I drove home with the heater on and it fluctuated between half way and three quarters on the gauge. I took out the stat and drilled the two 2mm holes, then I found it took ages to get warm and never rose about about 2/3 on the gauge. That's when I got a new stat and drilled one 1.5mm hole.

Works perfect now, warms up quick and sits at half way regardless of the heater control settings.

 

Helpful hint re. air-locks around the 'stat...
If you dont have a tiny drill, cut the edge of the actuator plate with a very sharp pair of cutters (or tiny tinsnips) in a small "V" shape about 1sq.mm or so so the air can get out. You may need to drop the 'stat in boiling water to make it easy to get at. If you have some warding files, use the triangular one on the edge to achieve the same result. You gotta get it right first time though, if you get it too big, you'll have to find the soldering iron... Also, the top hose is quite flexible to a strong pair of hands, so lots of sqeezing should dislodge any trapped air when hot. Keep an eye on the header tank level over a few days. Mine needed a small top-up, (as usual with jobs involving coolant), so I used some neat antifreeze left over from the radiator job. No trouble since I fixed the 2nd. 'stat in there.

Leedsman.

 

Thanks For That Leedsman and Matgriff

When i had the car running i did exactly that and squeezed the top hose with the cap off and the water was moving splashing around in the header tank in an attempt to expel any trapped air but then took the car for a drive to warm it up all that happened was the temp gauge got to its halfway mark which was a lot better the heater was hotter than before and the metal pipe on the side of the engine was hot to the touch but the top hose remained cold no matter what i did i did think of filling the hose with coolant then putting the stat back in but think i would have lost some connecting back up,, as it was there was still water in the pipe when i originally put the stat in there yesterday, i don't think the stat was opening otherwise the top hose would have got hot. i think the idea of cutting a V in the edge seems better for me than drilling....... as i don't have a vice to hold the stat in while im using a drill which could be dangerous for me anyway if the drill slips..... ill give the small "V" cut a go seems a like good idea ill try that when i next get on to it.... ill let you know how i get on BTW i managed to get one of those siphons like the one you have in the picture it works well too

Pete......

 

you don't really need a vice to hold the stat, as it will squash it. I just rested the stat on top of my workbench, wax pellet end facing up and used a new drill bit on the flat rim of the stat, not the part that moves. It's stainless so it was a bit harder than mild steel, but it was still easy. Just centre punch the hole spot first.

 

Peteandco, if your motor is a diesel, in this weather it will take a long time to warm up the rad. because diesels are so efficient compared to petrols. Nevertheless a small hole or a v-shaped nick in the 'stat's actuator plate won't harm. Try it with a much longer run, say 25mile or so with some hills if at all poss. City driving will also heat up the engine quicker. You may poss. find the temp. gauge stays nr. centre -- the gauge is the important part to check. BTW in this weather, the main rad. fans should not activate. A cold rad. is not necessarily a fault with a diesel in winter, esp. if you're using the heater. The last time I used a V-cut in a 'stat was in the 1960s. It was an old petrol car, worn engine and using oil, and by keeping temp below normal reduced the oil consumption. In those days with petrol at 25pence a GALLON*, I wasn't too bothered about the heavier petrol consumption!

Leedsman.
*Currently, petrol is just over £6 per gallonUK.

Addition: My 'stat says 82*C on it. I have a separate temperature gauge (my own) on the cylinder head which reads in *C. In winter it hardly ever gets above 78*C and I use the heater all the time full on. Therefore mine will never open under these conditions.

 

Hi Leedsman

The top hose was staying cool all the time while the rest of the engine was getting hot it was like the stat was causing a blockage and not opening that's why i took it out, Its because i did,nt make the small hole or v cut as advised and the stat did not open next time i do it ill make sure the v cut or hole is there before i put it back in to be on the safe side to ensure the stat can do its job

ill have to do it because it gets very uncomfortable driving in a cold car with hardly no heater as it stands the temp gauge only gets to a quarter and never reaches half way no matter how far i drive

Yours is a great idea Leedsman thanks for sharing this

Pete...

 

I just got to add that I got most of the air out of pipework when I did my thermostat by venting it at the bridging hose just off Stat on way to Radiator. I stuck a thin screwdriver under hose and removed it when coolant run out on filling tank. Finishing off by sqeezing hose at Radiator, rapidly.
And yes I remember petrol at 25p a gallon.

 

Hi goggs

Yes another good point ill try that next time i do mine it just a matter of getting the time at the moment but i will post in here after ive done it to let you know how i got on i still have the Renault 5 stat.. its just put away for the moment

pete...