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MG MGF Technical - Block & Piston cleaning!!


I am about to replace my cylinder head on my F tomorrow after HGF, I want to decarbonise the piston heads first and wondered if anybody had any tips on doing it?

I also need to flush the engine oil out as it was quite bad (creamy oil), whats the best way of doing this?

Thanks in advance

Wayne D


I wouldn't bother. With modern fuels and oils there should be very light carbonisation on the pistons. It's nice to see shiny pistons but you won't see them for long. The pistons, and the carbon on them, will have moulded to the liners very nicely, so you don't want to upset that,

I would (quite obviously) drain all the old oil you can, then refill after the engine work with your normal oil. You can leave the sump plug out and put in a half-litre to push out some of the dregs. Then top up and fire up. Change the oil after a shortish period, say 500 miles. Thereafter regular changes at the recommended period will clean the oil and keep it clean.

Regards, Kes.

I agree with Kes - the K doesn't seem to suffer much in the way of carbon depositation. Two reasons for suggesting this:

1. I've seen half a dozen cylinder heads off K-series engines of various mileages, and non have had excess carbon.
2. I once participated in a test of 'de-coke in a can' product for MG World. It released a few bhp from an elderly Porsche 944, but did nothing for my engine (it had been to Castle Combe the week before - which may be relevant, or not).

Getting rid of the mayo following an MGF is not especially easy - perform a complete system flush, and consider repeating a couple of times depending on the level of contamination.

Components of the cooling system that are particularly difficult to clear include the radiator. As your is highly likely to be badly corroded, you could consider early replacement with a new, uncontaminated component.

Good luck with the HG replacement :o)
Rob Bell

Thanks Kes and Rob

I've now refitted the head with new water pump and thermostat, a friend of a friend skimmed the head (10/1000ths/inch needed taking off due to corrosion!!)he also stripped the head and said the corrosion inside was quite bad so he did the valves and seals as well.

I left the pistons alone as you said but ran some new oil through the engine with the sump plug out, it seems to have done the trick but i'm going to give it a run to work and then do another oil change and flush.

The radiator is almost brand new anyway and the coolant is running clean from the bleed points, I think it was more of a case of water into the oil than the other way round.

Hopefully this will last a little longer than the last time, i'm averaging 40k between changes!!
Wayne D

Getting rid of the mayo following an MGF is not especially easy.
-Hope that is a typo Rob. :0)

ROFLMAO - I hadn't noticed doing that Charles... freudian slip perhaps? ;o)
Rob Bell

This thread was discussed between 02/06/2006 and 05/06/2006

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