Felicia 1.3MPi thermostat

[Rob_T]

Hi, I've found my 1.3 MPi Felicia doesn't heat up during normal driving even after an hour its barely above 70 though if I sit and rev it stationary it does go up. Had a read around on here and it seems that means its the thermostat. Going to order a MK 2 version thermostat from jorilly so it doesn't matter if the clips are broken. Though I'm unsure if I actually need to empty the coolant system or not, Haynes says I do, though drain plugs aren't included in the jorily kit which makes me think I don't need to ? any help or advice would be appricated. :-D

[GentleGiant]

What do you mean by heat up?? If it goes up when you rev I would suggest there is nothing wrong and you are a very lucky person, NOT to have a car that overheats in stationary traffic.

If I remember correctly the thermostat is near the top, so you may lose a little coolant and need to top up afterwards, but not need a full refill, unless you are due one anyway.

Drain plugs are reusable, so they would be in the kit anyway.

[Rob_T]

Hi GentleGiant, as I say it doesn't go much above 70 degrees during normal driving though I'm pretty sure it should be at 90 degrees. Just wanted to make sure when I change it I don't waste all my coolant.

:-)

[GentleGiant]

It might be your gauge is reading low, if the thermostat was duff the engine would be overheating.

Run the engine and see what it reads when/if the fan cuts in. If it cuts in the gauge is reading low, if it doesnt, then the engine really is that cool.

[richwarwicker]

my thermostat went and engine rasn cold not hot, as mentioned above, i didnt drain the cooolant despite the manual saying to, and i lost about 1.5 litres of coolant from the system when i took the thermostat off,. was a 5 minute job maximum!

[Rob_T]

Yeh it heats up when I rev as you would expect however driving with the engine at 70 instead of 90 seems to be a real kick in the teeth for performance and for fuel economy. (spending around 40 for what would normally cost 30-35). Being at the top of the engine was my theory for not emptying the coolant though wasn't sure how much I'd lose thanks for the info Rich, if its going to be 1.5 litres I guess I should empty the coolant first, guess I was just being lazy in trying to get away with not emptying it. Thanks for the advice :-D

[GentleGiant]

Why would running a bit cooler affect performance or mpg??

Less heat = less friction = better efficiency.

By all means stick a new thermostat or sender unit in, but I doubt it will make much difference to mpg.

[anewman]

Why would running a bit cooler affect performance or mpg??

A hot engine burns fuel more efficiently. It's the concept of the choke, in the cold you would pull it out to over-fuel to aid cold running and push it in when the engine is warm. A warm engine should equal better MPG, and I imagine a new thermostat would easily make it's money back in a year.

If it is the plastic thermostat, they are prone to breaking internally, which could lead to slow warm up and the type of symptoms described. Buy the improved thermostat from Jorily instead of one from a dealers.

To be honest I wouldn't waste my effort trying to do it with the coolant in, no doubt the coolant has not been changed in a while and if it's blue coolant (as opposed to pink/red) or looking murky/brown it's time for it to be changed anyway so you're sure exactly what is in the coolant system. I would also give the system a good flush with a hose at the same time and as you're removing the thermostat you can also back flush the engine block. If you do try to change it with coolant in the system try park pointing up hill, keep the coolant cap on, and put some rags over the top of the starter motor to prevent

Edited 25 August, 2010 by anewman

[GentleGiant]

70 Celsius isnt cold. Please remember this is the WATER temperature, not the engine; the engine generates heat that needs removing; if his water temp is a bit low it it is more likely his cooling system is working better than Skoda planned for, but it wont make a difference to how the engine performs.

[RobinSLXi]

70 Celsius isnt cold. Please remember this is the WATER temperature, not the engine; the engine generates heat that needs removing; if his water temp is a bit low it it is more likely his cooling system is working better than Skoda planned for, but it wont make a difference to how the engine performs.

Isn't cold relative to what? The engine is designed to operate with the WATER temperature at ~90 Celcius for maximum efficiency, therefore if the water temperature is lower, then the block temperature will be lower and the engine won't be running at it's best. Besides, 70 is about the minimum the gauge reads anyway (certainly in my car, even when switched off) so who knows what the actual water temperature is - all we have is an indication that it is lower than it is intended to be.

If "less heat = less friction" why does the majority of engine wear happen when cold? Why does the handbook tell you not to rev too high or accelerate hard until the temp. gauge has reached the middle? Indeed why have a thermostat at all? I had the exact same symptoms as the OP and I know my engine ran a lot more smoothly and used less fuel once I replaced the stuck-open thermostat.

@Rob_T: Unless you know it's been done in the last couple of years a flush and coolant change is probably well worth it - it's barely any more effort over changing the stat anyway. No need to replace the drain plug, although ideally you should use a new sealing washer when you put it back in. That said, if the old one looks in decent condition you may well get away with re-using it, even if it isn't recommended.

[GentleGiant]

Actually, it's the first few minutes, until the oil has been circulated and warmed, by then the viscosity has changed and allowed fresh oil to seep into all the nooks and crannies.

As for cool = better than hot. Look up thermal expansion; I would rather have an engine running a bit cool than one running too hot

Anyway, I still think it is more likely a gauge or sender unit problem, rather than the thermostat itself.

[RobinSLXi]

Actually, it's the first few minutes, until the oil has been circulated and warmed, by then the viscosity has changed and allowed fresh oil to seep into all the nooks and crannies.

As for cool = better than hot. Look up thermal expansion; I would rather have an engine running a bit cool than one running too hot

Anyway, I still think it is more likely a gauge or sender unit problem, rather than the thermostat itself.

Erm, the reason we have multigrade oils in modern engines is so that the viscosity remains relatively constant over a range of temperatures, specifically so that sufficient lubrication can occur before the engine has reached normal operating temperature. Because in "the first few minutes" the engine is colder than it would like to be.

Second, too hot doesn't come into it - I was correcting your claim that a cold engine is no worse than an engine at the correct temperature. Thermal expansion is the exact reason the engine needs to reach the proper temperature to run at it's best, so that e.g. the piston rings seal in the cylinder bores properly.

Whatever I think of your opinion, however, I can't contest that . It's just we're talking about a car with a well-known reliability problem with thermostats and housings showing typical symptoms of thermostat/housing failure (probably a broken off bit of plastic wedged in the thermostat preventing it from closing fully). And that's before I consider my own experience with the same issue.

[Rob_T]

:-S Didn't mean to start an argument, Sorry ! Coolant was changed when I replaced my radiator about 18-24 months ago so should still be ok, though thanks for the suggestion. I'll empty my coolant and do it. Thanks for your help everyone :-)

[ap0gee1978]

If you ARE changing the coolant, make sure you put the same stuff in, or flush thoroughly, since pink coolant mixing with blue coolant = brown sludge!

FWIW, when I put a new 'stat on SWMBO's MPi, I unclipped the forward-facing hose and drained what came out into a bucket to re-use it. But it was year-old pink (G12) coolant, so was OK to keep...

[anewman]

Yep undo the bottom radiator hose, if the coolant system drain plug goes iffy it's a bugger to replace the metal pipe.

[Rob_T]

If you ARE changing the coolant, make sure you put the same stuff in, or flush thoroughly, since pink coolant mixing with blue coolant = brown sludge!

FWIW, when I put a new 'stat on SWMBO's MPi, I unclipped the forward-facing hose and drained what came out into a bucket to re-use it. But it was year-old pink (G12) coolant, so was OK to keep...

Wish you'd posted that a few hours earlier! That is a very very good idea ! I already emptied and did the job when I read this though!

Yep undo the bottom radiator hose, if the coolant system drain plug goes iffy it's a bugger to replace the metal pipe.

Don't scare me like that :-P

All seems well, managed to wee out some coolant, wasn't expecting that much preassure! She now heats up nicely to 90 and I can't see any leaks from the drain plug. Had to order some G12 to top up as nobody around here sells it. Out of interest does anyone know if you can mix G12 with G30 ? (Both red)

Thanks again for all the help :-)

O just to add when I took the housing off, the metal bit (actual thermostat) inside was loose and not in position so I assume that was the problem (broken clip ?).

[ap0gee1978]

Yeah, the little lugs that hold it in place will have snapped off. Happens to all of them eventually unlees you swap it for the uprated one like you did...

[GentleGiant]

"She now heats up nicely to 90"

OK, I am man enough to admit I was wrong on what the problem was; I still dont think it makes that much difference to the MPG though.

[djaychela]

Well, it probably will do - the engine will be running richer, plus it'll be less efficient as the pistons won't have reached the correct clearance in the bores, let alone any other areas of increased friction...

[anewman]

I've never heard of G30, just G12, G12+ and the newer G12++ which can all be mixed from what I remember.

[bill123]

I put in a Mk II thermostat from Jorily and she runs at just over 70 deg when driving and goes up towards 110 in stand still traffic, rad fan kicks in. In the winter I have to cover part of the rad to have any hot air from the heater! I stick under the thermostat housing a small sink bowl catching around a litre and didn't loose any coolant.

[GentleGiant]

Is G30 the stuff that will mix with both "red" and "blue" anti freeze?? ( I know, organic and alcohol based!!)

[Rob_T]

Nah there was G30(Red) or G48(Blue) , The guy seemed to think they covered everything in existence and had never heard of G12. If nobody's sure then I prolly did the right thing to order the G12++ off of the internet (same price inc delivery so nothing lost). We'll soon see about the MPG but she certainly runs a hell of a lot smoother at 90.

Bill, do you just do short journeys ? If not and your car heats up ok when in traffic with no erratic behaviour of the thermometer reading on the dash then I'd think it might be worth testing the thermostat incase its faulty. Haynes has tests for the part though don't have it to hand to tell you what they are I'm afraid.

Thanks again everyone for the help :yes:

Good job Jorilly came along with an improved part so it doesn't fail again

[GentleGiant]

I HAVE seen some antifreeze down at the motor factors that says it is compatible with both.

[RobinSLXi]

G12++ should be also available off the shelf from any VAG dealer, about £6-7 a litre IIRC. I believe Halfords do a G12 equivalent too, but as with most of their stuff you end up having to scan the small print for the right specification (Haynes says TL-VW 774 C). I too am aware of a 'universal' type, which is compatible with both, but can't remember the details (I think I read somewhere that it's OK for topping up, but not really recommended for using on it's own).

@GG: Sorry for being a bit belligerent earlier, I wasn't having the best week. :S