loss of power when hot

[e30lou]

hi everyone, hope someone can help. I've recently noticed that when my 325i gets hot I seem to get a lack of power from it. I noticed today that in 1st gear I had to get up to at least 3000rpm before it moved away at a normal pace. I have also noticed that the fan is starting to make a woooooooooosh noise(if that makes sense!) and it's starting to become increasingly difficult to start when hot.

things have improved slightly since changing the fuel filter but not by a lot.

[parkin10]

blue temp sensor working?

[e30lou]

Have replaced it a few weeks ago and tested. Not sure where else to look, at a bit of a loss really

[Speedtouch]

Do the newspaper test on the fan: with the engine warmed up and at idle, stick a rolled-up newpaper in the fan blades. If it stops easily, then you probably need a new viscous coupling.

The theory being that, when warm, the viscous should lock in quite solidly to turn the fan blades.

What exactly do you mean by "when it gets hot" - where is the needle on the temperature gauge?

[e30lou]

Thanks Speedtouch, will try the newspaper thing.

When I say hot I mean running at normal temp, the needle is sat in the middle on the gauge.

[Speedtouch]

How many miles has it done? It could be worth doing a compression test on the cylinders - you can buy a Gunsons gauge for around £30 from Halfords.

You then remove all spark plugs, hold the throttle wide open and put the gauge into each spark plug hole in turn, crank the engine over until the reading settles and repeat for each cylinder. All should be evenly matched, and showing at least 150-160psi.

Any less indicates either piston ring/bore wear, or poor valve seating.

A very useful tool to have, as it will tell you alot about the condition of an engine.

[e30lou]

Oh right, I might do that then seeing as it's a failry cheap tool and like you said, seems quite useful.

It's just done 178k

[Speedtouch]

There's quite a few on E-bay:
http://www.ebay.co.uk/sch/i.html?_from= ... Categories

At that mileage, a compression check is definitely worthwhile.

Is the engine using significant amounts of oil? If it is, it's often a sign of worn piston rings/bore wear.