what's the deal with "head gaskets"

Foxy-Stoat_3

Its the Rover engine thing with them...I had a 216 (old shaped one) with the honda engine in my early years and commonly bounced of the rev limiter in most gears for a few years, never missed a beat.

redux

The head gasket on its own may not be the only problem, and it might be a short-lived repair if that's all that is done (like a Citroen I had done in Germany and it was bad again before I got home).

The cylinder head may be distorted and need a machine shop to skim it flat again. But there's only a small tolerance for being able to do that as the compression ratios will be affected, and not necessarily all the same. On some overheated engines the block may be distorted as well, so it might be necessary to line bore a set of new crankshaft bearings, or something like that. That might be why those Rover K engines were tricky..

googler

londonTiger wrote: »

Oh OK. So I presume if you were to add head gasket replacement into the long life service. It should come up to a reasonable £50 or something? rather than £500?

I suggest you find a motoring shop with an unsealed Haynes manual for your car, or find a library with a copy, and read the section that details what you need to do to replace the gasket, including cylinder head removal, inlet and exhaust manifold removal, and all the other stuff that has to be removed and replaced in order to get at the gasket.

Then ask yourself - would I do this for £50?

TrickyWicky

colino wrote: »

In short, the cost isn't the head gasket, it is the considerable labour costs involved that makes it expensive.

londonTiger wrote: »

Oh OK. So I presume if you were to add head gasket replacement into the long life service. It should come up to a reasonable £50 or something? rather than £500?

Did you not read the previous reply?

You have to physically dismantle most of the engine bay, dismantle the engine head (which in itself can take several hours), check the head for damage, check the cylinders, refit the new gasket, refit the head (usually with new head bolts), fit a new timing belt, tensioners and water pump, rebuild the engine bay... etc.

A timing belt change is usually £3-400. A head gasket requires dismantling of the top part of the engine AND a timing belt change.

If you really think it can be done for £50, please feel free to come and do my car work for me. In fact, if you're that cheap, I'll resell your services and pay for the advertising etc and we'll both make money (I'll charge £40 per hour and you can have your £50 for however long it takes). Seriously, PM me, I'll be quids in

motorguy

Foxy-Stoat wrote: »

And many don't reach 30,000 miles until the HG let go which is a joke.

Take a look how many are for sale on some online auction sites for spare/repairs with HG issues, same goes for Freelanders...they all seem to be on 60,000 miles with a new headgasket just fitted. Installs nothing but confidence...NOT

There were reasons why it happened and these were corrected by Rover via a number of revisions over a period of years.

It happens to many manufacturers - BMW with the 320d turbo problem, Ford with gearbox issues, renaults with electricals, etc, etc.

andygb

I have done four head gasket replacements on cars - MG Metro, 2 Alfas (twin cams), BMW 2002 - and all the cars worked better after. I also took the time to replace valve guides and reseat the valves in the head, and of course clean and polish the head.
If you do it yourself, then it takes time, patience and usually a lot less than £100.
It all starts to get messy when the head has cracked/warped, because that is the time to make big decisions - I was lucky, it never happened to me.

Gilbert2

mattyprice4004 wrote: »

If you have any MG/Rover with the K series engine, you'll always be told you have HGF, it's going to happen etc etc.

It's simply not true - many go on for 100k+ and are scrapped on their original gasket.
If they do go and the replacement is done properly, it shouldn't go again. They key is to fix the issue that caused the gasket to fail in the first place.

The problem with the Rover K series is the very small coolant capacity, a small leak can soon empty the cooling system, leading to HGF.

Depends what MG you are talking about because I don't know of anyone who didn't have hgf with an F.

HGF was more commonplace on the F than other MG's due to the location of the engine in the back & radiator in the front giving a very long cooling path & the location of the thermostat, as well as the small colant capicity you point out.

I had an MGF and suffered 3 hgf's and the last time it happened I was told to get rid rapid as it couldn't be skimmed anymore.

I was a member of an online site and nobody had a car on or over 100k who didn't suffer.

Dark days indeed.

Gilbert2

motorguy wrote: »

It happens to many manufacturers - BMW with the 320d turbo problem, Ford with gearbox issues, renaults with electricals, etc, etc.

That's interesting, my mechanic told me that he had never had to replace a gearbox on a Mondeo in 20 or so yrs.

Joe_Horner

Ford do make other models, you know?

http://www.autoblog.com/2011/10/27/ford-rushes-to-fix-gearbox-problems-but-not-quickly-enough-for/

Lum

The big issue with headgasket replacement is the cylinder head and block are nothing like the interface between, say, cylinder head and rocker cover. In the case of the rocker cover it's usually a bit of cheap bendy metal that needs to withstand low pressure from a bit of hot oil, it's usually fastened on with a bunch of standard bolts that any spanner monkey can put on correctly.

The head and block are solid lumps of metal. The mating surfaces are machined to be super smooth and if you screw up when lining them up you risk scratching one of the surfaces and rendering it useless. When the head gasket goes often the cylinder head will end up warped by a fraction of a milimeter, enough that you need to send it off to be machined back to flat again.

The whole thing is then secured by special bolts that are typically single-use-only stretch bolts. They need to be tightened down in a specific order, often in multiple stages.. get this wrong and you risk warping the head again and having to send it off again.

The whole thing needs to seal absolutely perfectly as it's got to withstand the pressure of the fuel burning inside the cylinder. You want that pressure pushing on the pistons, not pushing through the tiny gap where someone scratched the head, or through the manufacturing defect in the cheap nasty headgasket you bought off eBay.

It's a much more specialist job, and certainly not something you can get done by a Kwik Fit fitter.