VW Golf 1.6 FSI diagnosed with low pressure in 1 cylinder.

[wyson]

My VW Golf Mk6 1.6 fsi 2009 with 83k miles on the clock was diagnosed with low compression in 1 cylinder.

This manifested itself as rough idling and jerky acceleration and hesitation especially at higher speeds over 40mph.

My mechanic is suggesting the only sure fix is to replace it with a second hand reconditioned engine block which would cost about £2.5k fitted, all the ancillaries swapped over etc. He is saying the cause isn't obvious and stripping the engine to discover the exact problem won't be cost effective.

Are there any obvious cheaper things to try first? Seen youtube videos of people trying seafoam which can clear build up?

[stevieturbo]

wyson said:

My VW Golf Mk6 1.6 fsi 2009 with 83k miles on the clock was diagnosed with low compression in 1 cylinder.

This manifested itself as rough idling and jerky acceleration and hesitation especially at higher speeds over 40mph.

My mechanic is suggesting the only sure fix is to replace it with a second hand reconditioned engine block which would cost about £2.5k fitted, all the ancillaries swapped over etc. He is saying the cause isn't obvious and stripping the engine to discover the exact problem won't be cost effective.

Are there any obvious cheaper things to try first? Seen youtube videos of people trying seafoam which can clear build up?

Find a mechanic who can diagnose it properly. The cause will be obvious.

[tapkaJohnD]

I presume the guy has done a compression test. The next step would be to repeat with teaspoon of oil in each cylinder.

This will run down into the piston ring lands and improve the seal. If it does NOT raise the compression that the cause is a failed valve, sticking or broken. A sticking valve should be obvious if you run the engine without the valve cover. If not sticking valve then a 'borescope' down the spark plug hole may show the broken valve.

If it isn't a valve, but a piston ring seal problem, then it could mean a damaged piston or piston ring. That does need the engine dismantled to tell, unlee the borescope shows something.

A valve problem might be dealt with by taking off the cylinder head, but first you need a diagnosis. Yer man clearly can't be arsed to try.
John

[trevalvole]

tapkaJohnD said:

I presume the guy has done a compression test. The next step would be to repeat with teaspoon of oil in each cylinder.

This will run down into the piston ring lands and improve the seal. If it does NOT raise the compression that the cause is a failed valve, sticking or broken. A sticking valve should be obvious if you run the engine without the valve cover. If not sticking valve then a 'borescope' down the spark plug hole may show the broken valve.

If it isn't a valve, but a piston ring seal problem, then it could mean a damaged piston or piston ring. That does need the engine dismantled to tell, unlee the borescope shows something.

A valve problem might be dealt with by taking off the cylinder head, but first you need a diagnosis. Yer man clearly can't be arsed to try.
John

And with an early direct-injection engine, one might speculate that the valves being coked-up could be a possibility.

[GreenV8S]

A leakdown test can also reveal where it's leaking.

[Unweder]

Agree with both of above ^ also if they did a compression check they would have figures

[stevieturbo]

Really....proper tests are the right way to go. A basic old compression test or even leakdown can often mislead people ( if many even understand how to interpret readings ).

Modern methods are more definitive ( although this is obviously a healthy engine ), and this is just one quick option.

https://www.youtube.com/watch?v=6CcYPhtfKSk

[wyson]

Thanks all, armed with the knowledge from this page, I called up my mechanic who freely admitted he isn’t set up to diagnose this properly beyond doing a compression test.

So called an engine rebuilding specialist, he basically said, no matter what the fix won’t be cheap, £1.5k to rebuild the head at best and double that if the bottom end has gone, or maybe something in between, depending on the problem.

Even the best case scenario presented on this page of deposits in the cylinder head, cleaning that would cost £300, and would prob need another £100 of diagnostics to get there (standard starting rate in London it seems) + trailering costs as I've been told not to drive the car as the engine could go at any moment.

Decided at this stage to get rid. I suppose if this happened to a 5 year old car worth £10k, my calculation would be different, but at this stage on a 13 year old, £3k ish car, I think it will be less headache to just cut my losses and buy a nearly new car.

Thanks all. At least it was an education!

Edited by wyson on Sunday 22 January 12:24

[stevieturbo]

A drastic decision perhaps with such a poor diagnosis.

But then also slightly understandable given potential labour costs....to still not always get a safe outcome.

It really should not be so difficult to get good honest/competent garages/technicians....but it just seems to be that way

Good guys should be paid well for their services, but the industry is rife with bad ones, who charge even more.

[wyson]

stevieturbo said:

A drastic decision perhaps with such a poor diagnosis.

TBH, I have been thinking about getting rid for a while and this is the final nail in the coffin.

My modus operandi is to buy low mileage nearly new cars, then run out the original components and sell before lots of stuff needs replacing. I kept this car longer than I would like because of the current madness in the economy. If it wasn't for covid, lockdowns, car prices going nuts because of supply issues, cost of living crisis etc, I would have sold it a couple of years ago.

Totally appreciate that different people will have different ways of running cars, but I want something pretty reliable, that will just work.

Honestly if I were retired or something, I could get into solving this, maybe even hire a space in a workshop and have a go myself, but with young kids my priorities lie elsewhere.

Edited by wyson on Sunday 22 January 14:08

[wyson]

I was thinking about getting a second diagnosis, but was told the engine might go kaput at any moment and not to drive the car.

Trailering the car to a mechanic who could do a full and proper diagnosis was yet additional expense and hassle I didn't want to deal with.

Currently I'm thinking the most headache free way out is to sell it for spares or repairs and let someone else trailer it away, or accept the risk of driving it.

[wyson]

stevieturbo said:

It really should not be so difficult to get good honest/competent garages/technicians....but it just seems to be that way

Good guys should be paid well for their services, but the industry is rife with bad ones, who charge even more.

My current mechanic is honest and fine for routine servicing but said it isn't worth his while to invest in the specialist equipment for this sort of diagnosis. I don't think he really wanted to deal with it and told me to contact an engine rebuilding specialist who does this day in day out.

Both of them told me not to drive the car!

Edited by wyson on Sunday 22 January 14:10

[stevieturbo]

wyson said:

My current mechanic is honest and fine for routine servicing but said it isn't worth his while to invest in the specialist equipment for this sort of diagnosis. I don't think he really wanted to deal with it and told me to contact an engine rebuilding specialist who does this day in day out.

Both of them told me not to drive the car!

Edited by wyson on Sunday 22 January 12:49

TBH, a lot of diagnosis is just knowledge and experience. Some have it, most do not. Equipment can help, and a lot of the stuff needed is not expensive at all in the grand scheme of things.
But a lot of "mechanics" never get past the parts changing level, or parts cannon level. Whether they are unable, don't care, who knows.

But yes, continuing to drive the car in this condition will certainly not be a good idea.