Changing factory heat exchanger / oil cooler..

[Jim 2]

Hi..

 

Just wondered if anyone has ever replaced the factory oil cooler on their 1.8 or 2.0 16v before and if so, is it a big job? Trying to get to the bottom of why my car runs warm (just ordered ANOTHER new rad fan switch after we found my 2nd genuine VW one isn't working properly......) and I think i'd like to change the oil cooler just to be sure it's not bunged up or something and causing my high engine temperatures..

 

I don't really want a Mocal because if the cooler is bunged, it's not actually fixing the problem but instead working around it - I'd rather know the cause of the problem before I think about bolt on upgrades like the Mocal. Additionally the factory cooler should easily cope with running a pretty standard 2.0 16v for non-track driving.

 

I've searched to death on here and Club GTI and all I can find is chatter about fitting a mocal - and never just working on the existing heat exchanger. Big job? Small job? Cheers.

[boost monkey 0]

I've taken one off when stripping an engine Jim. It's not too bad, you'll need allen keys to get the bolts out and the cooler itself is held onto the main stalk (bit the filter screws onto) with a reeealllly thin 32mm(?) nut which is kinda fiddly to get off as it's done up quite tight and I was using a monkey wrench as I don't have a socket that big.

 

I'm just trying to think what else you need to take off to get to it. Apart from oil filter!

 

I think a lot of people leave them in situ even if they get a Mocal, as it helps the engine warm up quicker by transferring the heat between oil and coolant on cold starts / frosty mornings. :salute:

[aide 0]

yeh easy enough as noted above, remove the nut (which may turn shaft thing also) and it slides off

 

you'll obviously have to drain down coolant and oil!

[boost monkey 0]

ah yeah, coolant and oil. :nuts:

[Toad 0]

It's not too bad Jim, I changed mine. Main issue is getting the coolant pipes off which are awkward (for a change :roll: ).

 

I can give you a hand some time if you fancy?

 

Might be worth looking at replacing the hoses that fit it, at the time.

[Jim 2]

Thanks for the responses guys.

 

Stuck my head under the bonnet today after the little session at DG Autotech yesterday and was actually surprised to notice that the coolant pipes into the oil cooler look as though coolant has been bursting to come out so it's kind of bubbled out of the sides and dried on - possibly lending more thought that the oil cooler might be a bit gunged up and it's allowing coolant to flow through properly.

 

Will investigate costs of bolts / hosts / the cooler from VW, Tom, and get back to you. Wouldn't mind trying to do it sooner rather than later though as my car isn't liking this hot weather much :(

[Supercharged 2]

At that mileage it's a good part to change mate if it is original!

 

You won't have got 2 faulty VAG fan switches btw, either the rad is never getting hot enough or you have a wiring issue ...

[Jim 2]

I keep thinking it's just that coolant isn't circulating properly - and the cold coolant is just sitting in the bottom of the rad down where the fan switch is! But Dave and Graham had a laser temperature sensor on my car this weekend and found the coolant pipes to be not only way too hot (95 centigrade when they'd expect to see them about 80) and also very very hard...

[Supercharged 2]

Bypass it with a U bend or 2 MK1 water pipes - see if it makes a difference

[davidwort 0]

do you have the heater matrix by-pass valves fitted Jim, if so I'd suggest removing them and linking the water hoses temporarily to see if the matrix is restrictive. It's easy enough to see if the by-pass valves are operating correctly by blowing through them, dry off the car obviously.

The other possibility, and perhaps the worst, is that the headgasket is possibly starting to go.

It's not a bad idea to change an old oil cooler but I don't think that would cause high water temps.

[dragon green 4]

Jim

if you do get round to doing this,could you take some pics please ?

I`am sure mine runs a little hot aswell, and have often thought of the mocal route

[Jim 2]

do you have the heater matrix by-pass valves fitted Jim, if so I'd suggest removing them and linking the water hoses temporarily to see if the matrix is restrictive. It's easy enough to see if the by-pass valves are operating correctly by blowing through them, dry off the car obviously.

The other possibility, and perhaps the worst, is that the headgasket is possibly starting to go.

It's not a bad idea to change an old oil cooler but I don't think that would cause high water temps.

 

I've no idea mate - I don't know what the bypass valves look like :( Dave and Graham had suggested that it could also be a blockage in the heater matrix.. TBH I'm thinking about just dropping the car with them and letting them poke and prod about to find the cause!

[boost monkey 0]

ok, locate where the two coolant lines pass through the bulkhead and connect to the matrix. If the hoses go all the way to the bulkhead then you don't have the valves. If however you have something small and metal connected in line with these hoses near the bulkhead then you probs have the valves.

 

hth,

 

Jon.

[Jim 2]

Cool - cheers mate. Will have a look when I dig the car out next.