Hi guys

 

I have started experiencing a strange problem with my Mk1 vRS - it runs fine when cold but once the engine has warmed up it loses a lot of power and becomes pretty gutless. It has also started to overheat which it has never done before, but the power loss is there even with the temperature right at 90deg where it always normally sits.

 

I have checked with VCDS and it didn't show anything that I could see (there were a few codes such as 'Radio - no communication' which I get all the time because the HU has been changed, and one for the rear right door lock implausible signal, but nothing engine related or sensor related) however if I reset DTC's then it seemed to sort the problem out temporarily, but it quickly returns.

 

It is a high mileage engine having done 205k miles now and it does need an overhaul or replacement (blue smoke) but it has always driven well so this is a little unexpected.

 

Does anyone have any suggestions on what might be causing this? Would a packed in water pump and higher temperature cause the engine management to go into a protection mode?

 

I will give it another scan tonight and see if anything new has appeared.

 

Thanks in advance.

If its over heating if could be water pump or thermostat. As for the poor running when warm could be the coolant temp sensor. Had you tried running it with the maf unplugged?

is the guage sitting at 90 when warm at all times?

Tried running without the MAF and no difference, but it's definitely not circulating coolant and now the temperature is reaching 120 and showing the warning light. Normally, it's sat on 90 like it's been painted on, never seen it above that.

 

I replaced the water pump with one with a metal impellor in the past so hopefully it hasn't actually stopped running and it's a thermostat fault, but would that explain the loss of power?

 

VCDS shows nothing engine related except the MAF sensor which I unplugged today.

The car will lose power if its to hot. Chances after 200k miles the thermostat is duff and staying closed or the waterpump. Thermostat will be cheaper and easier to replace first

Thanks, sounds like the first thing to do then.

try just pulling the thermostat to see if there is any water flow around the system (thermostat can be tested using a bowl of boiling water to see if it opens) - youi should get a flow through the small pipe at the top of the expansion bottle with the engine up to temp - if not the water pump would be the culprit

If the thermostat valve is jammed shut, your engine will noy circulate coolant through the radiator, in which case the pipe will not feel hot (caution! ) obviously heat of the engine will propagate but you read like you have at least 1 working braincell, so locate the thermostat and follow the tubes to the radiator. 1 will always feel cold, the other will vary in function of engine heat. Best to start with cold engine, come 90ºc, the valve should open fill the top of radiator with boiling water

These valves are designed to fail on open though, not shut, is this a genuine part or 'oem'?

I would stop driving asap & get this looked at.

The car is off the road unil the end of the week when it's getting looked at - it's actually hardly moved for the last couple of weeks anyway as I've been using the motorbike instead.

 

... you read like you have at least 1 working braincell ...

These valves are designed to fail on open though, not shut, is this a genuine part or 'oem'?

lol Thanks, I think

 

As far as I know it is the original part, I don't remember having replaced it and I've had the car for 8 of it's 11 years.

Mine failed after 9. See how it goes and let us know your findings

Will do. On the way to drop it off I checked that the interior heater is working and it's getting hot pretty quickly so it looks likely that the coolant is being pumped around after all. I'll find out tomorrow.

It was just the thermostat in the end, all fitted and fixed for £25.

Good news, hopefully a genuine one was fitted.

Brilliant!