I need to check the tension of the timing belt on my renault 19. The car has suffered several water pump failures in a short space of time. I have learned in this NG that an overtight timing belt may be putting a strain on the pump causing premature failure.
I have an official renault manual for the car which describes how to check the tension. Apparently, a special tension gauge is used. A force of 3 daN is applied to the belt at a specific point and the belt should deflect by 6 mm when cold. Now this tool seems to be a renault specific thing so probably only supplied to renault dealerships. But the question is - is there some sort of tool I can buy in a motor factors which will do a similar job. Or is there any other "trick" for checking the tension without using a tension gauge?
Thanks for that. But look at the prices! 70 UKP for the cheapest one. A new water pump is a lot cheaper than that - might be more economic to take a chance on the tension being OK and if the water pump fails again then so be it. Still, I'll consider getting a gauge, thanks for the info.
I've read that a reasonable check is that you should be able to twist the belt - at the middle of the longest run - through 90 degrees, using just thumb and finger.
Like most mechanics I have installed hundreds of belts but don't use a tensioner gauge, no belts have failed. If there is a straight length of belt between cogs that is about a foot long then the twist 90 degrees with the fingers trick is right, if the gap is half that then only about 45 degrees is right, the main thing is that when installed the belt should not be really tight or something will fail. if the belt is so loose that it hits the covers, then that is too loose.
The car hasn't been near a Renault Garage for years. I just got fed up paying outrageous prices for parts/labour for what is after all a pretty old and low value car. So I have been buying genuine parts from Renault and getting my own mechanic to fit them and it has worked out very well except for the problems with water pumps.
This is the method my mechanic used. There have been no problems with the belt itself and it gets changed every 40k miles (I believe the manufacturer recommends a change every 72k) The first belt change was done by a Renault garage at around 50k miles and they did not change the water pump. The original water pump in the car lasted 6 years/85k miles before it started to weep. In the 2 years/40k miles since the original pump failed, the car has had 2 new pumps and now it appears that yet another new pump is needed.
I just thought of another possible cause. The cooling system seems to be prone to corrosion. The coolant needs to be flushed and changed regularly or it becomes a rusty brown colour (common renault problem I believe) So, I'm wondering if particles of rusted metal could be getting wedged in the inner seal of the pump causing it to fail prematurely? Does this sound possible?
Definitely possible - have you got the correct concentration of antifreeze in there (most manufacturers recommend 50/50) - do you know if the coolant has ever been changed? If it's been leaking and you've been topping it up with water this would weaken the concentration, and in turn reduce the effectiveness of the anti-corrosion properties of the antifreeze (which wane in time anyway).
And that is not neccessarily a common renault problem, but a common problem with any car where coolant changes, or the wrong concentration of antifreeze (or none at all) have been ignored or neglected.
Recently in my Fiesta van (W/2000 1.8TDi) I had a coolant leak which I strongly suspected was due to the garage who changed the aux drive belt (this drives the water pump on mine, not the cambelt - and it shredded on me!) topping it up with the wrong type of antifreeze. They used the blue/green coloured stuff, and the stuff that was in there was the more modern specification stuff (pink/orange in colour). Ever since then I was losing coolant and had to top it up regularly. Eventually I got around to draining it and flushing it through. I drained as much as came out (from the drain plug at the bottom of the rad), which was probably only about half the capacity, flushed it through by pouring water in through the expansion tank and waiting until it ran clear from the bottom of the rad, then topped up with plain water, run it around for a bit so it got up to temp, then drained it again (thus flushing it around quite a bit anyway, and also getting rid of a lot more of the older stuff), then flushed it through again. Then topped it up properly with enough pure antifreeze to constitute half of the specified coolant capacity, then a bit more water, and the leak has been completely cured. After about a day of use the level had dropped a bit, but it's stayed at that level for the last few weeks (and lots of miles) so I'll need to go and get another bottle of antifreeze (the correct stuff this time) and chuck some in a bottle so I've got a top-up bottle with the right concentration, then top it up to the top.
Anyway, my theory on what happened goes like this - the combination of two vastly different types of antifreeze (which all the manufacturers say should
*never* be mixed) have completely different chemical properties, and there was basically a reaction between the two types, forming some sort of crap that seeped through the main water pump seal (or just lodged in there, leaving a gap so other stuff could seep through), and left an ugly looking mess on the outside of that whole area. Flushing it through a couple of times with clean water dislodged this crap, resealed the system, and hey presto, no need for a replacement water pump (which I thought I'd have to cough up for).
Does anyone reckon the above theory actually could be about right, as it's the only way I can explain how just flushing the system through, and topping up with the correct concentration of just the *one* type of antifreeze could cure such a leak.
They're not using a strong enough anti-freeze mix. 25% only provides protection against freezing only and not against corrosion. 33% mix should be considered the minimum.
I agree it would be nice to have every tension gauge going, but it is impractical. Since I rarely need to change water pumps on my regular cars I assume that the tension by feel method is ok. However, when changing 214 belts I insist on changing the pump at the same time since they fail at about 40 thousand anyway.
It has never been topped up with water and has only ever had renault premixed coolant put in it which is a mixture of ethylene glycol + distilled water + corossion inhibitors at the correct concentrations. Coolant has been changed several times in the past 3 years.
Cooling systems do seem to be a weakness on Renaults. I've owned a succession of the things and the coolant usually starts turning brown when the car is around 1 year old. And if you go more than 2 or 3 years without changing coolant, it will have the appearance of gravy. In contrast, I know people who drive japanese and german cars and the cooling systems seem far more robust and the coolant doesn't need changing as often. I don't think I've ever seen gravy-like coolant in a german or jap car unless it's been severely neglected. Yet I've *never* seen a renault more than two years old which didn't have at least some signs of dirty coolant. Also seems to be a problems on peugeots and citroens.
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