P38 under powered and overheating

I'm having a problem I'm hoping someone can help with.

I've a p38 4.6 which is really down on power and overheating. The lack of power is constant. When I'm on the motorway it will cruise happily at 55-60 with no probe, but as soon as I give it any beans to overtake etc, the temp goes right up to the red, ease off to cruise at 60 again and temp drops back to normal.

It has been leaking coolant a little, topping up half the header tank per week for a few hundred miles use, and ended up mixing red and green coolant as it's all I could get hold of at the time it was overheating. Had thought that was the problem but I've now changed the coolant completely and still getting the same problem.

It's converted to LPG, but get the same problem running on petrol

Overheating - air lock / stuck thermostat / knackered water pump / head gasket failure / block failure / slipped liner
Lack of power - not enough fuel / low compression
Overheating AND lack of power - probable head gasket failure which could also give you low compression on one or more cylinders

How long has it been doing this? Any other symptoms? Ok when left idling?

:behindsofa:

Dunno whether it's just me, but P38's running on LPG just seem to give more problems than the petrol only versions and a lot of them relate to overheating issues which most of us know is a killer with the V8 or poor running.

Derek Ward said:

How long has it been doing this? Any other symptoms? Ok when left idling?

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it started about 2 weeks ago but been on holiday for 10 days so it hasn't been used, so only recent issue. No other symptoms I can see so far. When idling it runs perfect and revs fine too, just seems to be when under load.

My lack of power under load was a shot MAF sensor, but I had no overheating issues. It could be a coincidence and the lack of power and overheating might not be related.

On the other hand if there is no visible signs of the coolant loss it could be an internal leak to the head gasket. Any white smoke out of the exhaust?

fortgrange said:

On the other hand if there is no visible signs of the coolant loss it could be an internal leak to the head gasket. Any white smoke out of the exhaust?

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There is a bit of coolant loss, have to top it up once a week, just within the header bottle. There's no white smoke from it tho

Buttas said:

There is a bit of coolant loss, have to top it up once a week, just within the header bottle. There's no white smoke from it tho

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If you are topping up with no visible signs of an external leak it means you are losing it internally which probably means a head gasket. Any decent garage should be able to test the coolant for exhaust gases to confirm this.

Quick update, just disconnected the MAF sensor and took it for a run and same issue so i think that's it ruled out

You need to get a block test done mate as been said before any decent garage should be able to do this at a reasonable cost as it only take about 10 mins once the engine has warmed up.