General How To.... Diagnose a K Series Head Gasket Failure

[1955diesel]

The K Series engine has gained itself a bad reputation for head gasket failure and not without some justification. However, this has become something of a vicious circle with gasket failure often being diagnosed simply because “Rovers have gasket failure”.

The main weakness of the original elastomer type gasket was that the rubber sealing beads would become crushed or displaced due to the effects of heat and the shuffling movement between head and block. The Service Fix MLS (multi layer steel) gasket design eliminates the rubber beads and provides a smooth, hard surface to accommodate slight movement. A further revision to this gasket is now available from XPart which requires the use of higher tensile bolts.

And just so that we all know where it is, here is a picture -

General Layout

Production Elastomer Gasket


MLS Gasket and Shim.



The symptoms that do not usually, on their own, indicate failure –

• Coolant Loss – almost always just a common coolant leak. If it is leaking past the head gasket, it will show up running down the side of the block, in the oil or in the cylinders (more on this later).

• Oil Loss / Oil Leaks – probably due to cam cover gasket leaks, camshaft seal leaks or oil burning due to worn stem seals. If due to the head gasket, it will show in the coolant as mayonnaise, but hardly ever as an external leak since most of the periphery has only coolant behind it.

• Overheating – mainly due to cooling system problems such as non functional fans, coolant leaks causing low level and subsequent air locks, sticking thermostats etc. but it could be caused indirectly by the gasket. If coolant is leaking past the gasket fire rings into the cylinders, then combustion gas will be leaking back the other way. In most Rover installations, this will quickly result in gas pockets forming in the heater/by-pass circuit causing the heater to go cold and the engine to boil up.

• Loss of Performance – could be almost any combustion related fault, but almost certainly nothing to do with the head gasket. For a gasket problem to affect performance, it would have to be losing so much compression or consuming so much coolant that a major problem would be apparent. The exception here is when a head gasket leak has caused the system to boil up (see Overheating above). If this is not detected, the engine can become so hot that it begins to lose performance. This is a fairly terminal stage!

• Mayonnaise under the Oil Cap or on the Dipstick – a very pale deposit of oil emulsion is common in winter and in engines where the oil never gets fully hot. Of course, it could also be the very early signs of gasket failure if associated with coolant loss, but let's not jump to conclusions just yet.

• Steam/Water from the Exhaust – Rovers tend to be steamy in winter and also drip water from the exhaust. This is due to condensation, but may be made worse by an inlet manifold coolant leak. If it is losing coolant into the combustion chambers due to a head gasket leak, the combustion gas coming back the other way will be causing air lock type problems.

• Discoloured Coolant – if it looks like dirty water or there are solid deposits in the header tank, this is probably due to old coolant and system corrosion. However, oily emulsion in the coolant is usually a very bad sign.

• Hoses Splitting / Blowing Off – The system pressure is governed by the filler cap valve and all components are designed to easily withstand this. Hose problems are usually due to deterioration (perhaps caused by oil contamination) or loose clips. Also, hoses should not be lubricated with anything other than soapy water to ease fitting.

• Emissions Problems - There must be 101 reasons for failing the emissions test and some of them may be caused by head gasket failure damage. The Lambda sensor and catalyst in particular do not like to be contaminated with oil and water. But generally the problem is due to some other reason.



The symptoms that indicate a strong possibility of head gasket failure –

• Mayonnaise in the Coolant Header Tank – a thick, creamy scum collecting on the tank walls and in the coolant. However, this could also be residue from an earlier failure as it is hard to clean it all from the system.

• Emulsification of the Oil – not to be confused with light mayonnaise deposits, in this case, the oil itself will turn to the consistency of chocolate milkshake and there will be heavy mayo deposits (creamy sludge) under the filler cap. There will also be associated coolant loss. However, it can be a difficult call because minor mayo deposits may first show before they increase to this terminal state.

• System Boiling due to “air locks” in the heater/by-pass – Rover cooling systems are poor at getting rid of gas. Air locks can result from running low on coolant and are usually first indicated by the heater blowing cold air instead of hot. If they keep coming back despite bleeding, it may be due to combustion gas escaping past the head gasket into the cooling system. This may occur due to the engine having low liner heights or softening and subsequent indentation of the head face. These faults will cause low clamping pressure on the gasket's fire ring and leaking of combustion gas past it into the coolant. Problems can also be caused by porosity of the head casting. These voids in the casting can be uncovered during skimming of the head face and it is recommended that the fire ring area is lightly peened to compact the surface before machining. The shim supplied with the MLS type head gasket is supposed to seal off any porosity.

• Coolant Leak running down the block – often from beneath the exhaust manifold could be from the head gasket, but is sometimes from the inlet manifold gasket as it runs around the head joint before showing itself. Look for rust or coolant stains on the front face of the block. Head gasket leaks in this area are usually caused by the rubber sealing bead deteriorating and becoming displaced or crushed. However, there have also been reports of new MLS gaskets leaking in this area. So far, these seem to be confined to unbranded gaskets - another reason to stick with the OE supplier of Payen.




Are there any tests to confirm head gasket failure?

I’m afraid not or at least none that are 100% reliable. There are three commonly used tests, but none will give a definite answer.

• Sniff Test – detects combustion gas in coolant. As mentioned above, Rover’s cooling systems generally become air locked and boil up at the first sign of combustion gas leaking past the head gasket. The test is also not that reliable in my experience giving both false +ve and –ve results on occasions.

• Compression Test – measures pressure in the cylinder during cranking. If the gasket fire ring is leaking sufficiently for it to show on a compression test, you will already be experiencing persistent air locks in the cooling system.

• Cooling System Pressure Test – may detect a head gasket leak, but the coolant loss will have already shown itself in the oil or externally.




So Where is my Coolant Going?

Coolant leaks can often be difficult to trace because they leave far less evidence than people are expecting. It is not often that they drip on the floor so that you can see where it is coming from.
The common leak points are -

Water Pump - you need to remove the cam belt cover to look for staining under the pump. They often dry before showing on the outside and can be intermittent. See - http://forums.mg-rover.org/showthread.php?t=264710

Inlet Manifold Gasket - in addition to the obvious external leaks, they can leak internally directly into the engine intake ports. This can not be detected from the outside and replacement is the only real test. It may result in a start up misfire and extra exhaust steam or show as a change in colour of No1 or No4 spark plug tip. This is mainly a problem associated with the plastic manifolds. Metal ones such as VVC tend not to suffer, but are probably not immune. See - http://forums.mg-rover.org/showthread.php?t=213626

Radiator / Hoses / Plumbing - most of the evidence will blow away in the wind or dry up so you are only looking for traces of staining and dried antifreeze deposits. There are common corrosion problems with the metal pipe running to the thermostat and also the under body pipes on MGF ect. The radiators on the MG seem to suffer badly too.

Coolant Filler Cap - a leaking cap can lead to unexpected boiling, but the venting of vapour can also show as a slow coolant loss.


For more information about coolant loss see - http://forums.mg-rover.org/showthread.php?t=335685


What about changing it Just in Case?

The general consensus is no. Head gasket failure on the K is not inevitable and there are thousands of examples of it never happening. You can also minimise your chances of a problem by making sure the cooling system is in first class condition, the coolant changed when required and kept up to strength and perhaps a low coolant alarm fitted. PRT type thermostats were fitted to later cars and this should in theory give the gasket an easier life. In practice the rate of failure was not reduced to any great extent.


How about using a cooling system sealant?

This is a subject surrounded by controversy! Some say that it clogs up your engine and wrecks it, others that they have used it successfully. The truth is probably somewhere between the two and depends on the type of failure that your engine is suffering from. My own view is that it is best held in reserve for emergency use or to try to keep a car going that would otherwise be scrapped. The other occasion when I might be tempted to try it is if everything was known to be in good condition, but a newly fitted MLS gasket had an external leak. In this case it would probably work and the parts should remain in good condition for some time afterwards. It is not like trying to seal rust or a rubber sealing bead that is on the move.




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I expect there will now be lots of posts about odd symptoms that were cured by replacing the gasket, but I suspect that many of these cures will be due to other changes made during the head gasket work. Eg. Inlet manifold gasket. Most of the symptoms are also subjective and hard to interpret without being there and having had past experience and there are always exceptions to the rules.

[slickman]

should be made a sticky, instead of the same question 3 times a day lol, "have i got HGF"

nice one deisel.

[MyMgCar.com]

Thats a lot of effort writing that, definitely should be a sticky mate

[1955diesel]

For the uninitiated, emulsified coolant/oil looks like this -




although this shows oil contaminated with coolant, the coolant/oil mix you might find in the header tank looks similar.

(image borrowed from another post on this forum - not sure who to credit for it)

Edit: posted by MGFNorway. Thanks.

[gotenks1321]

Originally Posted by 1955diesel

For the uninitiated, emulsified coolant/oil looks like this -




although this shows oil contaminated with coolant, the coolant/oil mix you might find in the header tank looks similar.

(image borrowed from another post on this forum - not sure who to credit for it)

I think that's Broon's but might be wrong

[Swalesy]

Brilliant mate Good job

As Slickman said this should hopefully stop the question being asked 3 times a day

Has this been made a sticky yet?

[Dr.Buck]

Cracking little note there, diesel!

Point 5 under 'symptoms that do not usually, on their own, indicate failure' is helping with a bit of paranoia I keep getting (a thin layer of what looks like vaseline, rather than mayo, inside the oil cap every now and then, it comes and goes on it's own!)

+1 for sticky status!

[robchester]

So is HGF common in all K-Series engines? I know that the 1.8 had a particular problem with the cooling system not being big enough but do the 1.4's and 1.6's suffer just as badly?

I had a 218iS a few years back (kinda miss it) and now im returning to cheaper motoring, i fancy picking up a very affordable 25 but avoiding the 1.8 as mine too suffered HGF

[1955diesel]

Yes, they all suffer apart from the earlier wet liner engines. The reasons are multiple and the occurrence almost random.

[Rovernut]

With my experience of owning three k series cars which have all had gaskets replaced, I would like to humbly suggest another clue.

When you start it up in the morning and it seems to run on 3 cyls for a few seconds, I reckon that'e due to a gasket leaking coolant into that cylinder.

Anyone else experience that?

Chris

[skrib]

my cars silver does it have hgf?

[skrib]

Originally Posted by Rovernut

With my experience of owning three k series cars which have all had gaskets replaced, I would like to humbly suggest another clue.

When you start it up in the morning and it seems to run on 3 cyls for a few seconds, I reckon that'e due to a gasket leaking coolant into that cylinder.

Anyone else experience that?

Chris

just out of interest cos i dont think ive ever experienced this......how woudl u know ur runngin on 3 cylinders.?

[1955diesel]

Originally Posted by Rovernut

When you start it up in the morning and it seems to run on 3 cyls for a few seconds

Sounds more like inlet manifold gasket if there are no other symptoms.
However, there are always exceptions with engines. After working with them all my life, they can still catch me out.

[skrib]

Originally Posted by 1955diesel

Sounds more like inlet manifold gasket if there are no other symptoms.
However, there are always exceptions with engines. After working with them all my life, they can still catch me out.

where on the engine would u be able to see this leaking?

[MGJohn]

A friend had her R25's cylinder head gasket replaced along with a replacement cylinder head recently. Within a few miles of having the job done, the car boiled over and had to be recovered by trailer.

I looked at the car and offered to replace the cylinder head gasket again with the multi layer type and its head saver shim. Actual replacement of the cylinder head gasket was a doddle. Cleaning all the oil-coolant mix from the engine and the whole of the coolant system wasn't ~ it was a lot of work.

What I found was during the previous repair, the essential dowel which not only locates the cylinder head correctly to the block, but also encloses the essential oil supply to the over head camshafts .... was missing! This allowed the engine oil being sent at high oil pump pressure to the Over head cams to be diverted into and around the cylinder head and its gasket. This in turn meant it was sent into the cooling passageways and the rest of the cooling system at oil pump pressure. I fitted two new steel dowells in place of the nylon ones which very positively located the cylinder head and, more importantly, enclosed that oil supply.

To the inexperienced, at first this would appear to be yet another misleading "They all do that ~ repeat HGFs are common ~ well known fact" scenario.

WRONG >>>>!!!!

This is yet another example of incompetent repair workmanship. Apart from that one little (BIG!) omission, they had done an excellent job. Since I repaired the engine, the car has done in excess of 1000 miles including several long motorway speed runs so far without further incident. The odd trace of oil has appeared in the coolant bottle ~ I suspect that is remnants from the previous failure which no matter how carefully and thoroughly you clear out the old much from the previous 'failure', a few globs of the stuff still lurk in the corners of the cooling system. This is what the stuff looked liked when I flushed the totally blocked core of the radiator:



This is what I saw when i first lifted the bonnet:



and on removing some cooling pipes and radiator:



The stuff was everywhere and took several hours of cleaning to get rid of most of it from engine and cooling system.

The full story can be found on this thread:

http://forums.mg-rover.org/showthread.php?t=234493

This is one of the worst cases of incompetent repairs I've ever seen on a car and I've seen many such over the years I've been driving. In conclusion, please remember this:

THEY DO NOT ALL DO THAT!

Only some.....Unfortunately, due to incessant K-Series media negativity overkill ~ that is a LITTLE known fact.
.

[1955diesel]

Originally Posted by skrib

where on the engine would u be able to see this leaking?

(inlet manifold gasket)

They often leak coolant internally into the inlet port. The only way to tell if this is happening is to replace the gasket. New ones have a different profile and material (green colour). This is usually done when the head gasket is changed so the symptoms stop even though the head gasket was not the cause.

[skrib]

Originally Posted by 1955diesel

(inlet manifold gasket)

They often leak coolant internally into the inlet port. The only way to tell if this is happening is to replace the gasket. New ones have a different profile and material (green colour). This is usually done when the head gasket is changed so the symptoms stop even though the head gasket was not the cause.

sounds like peopel could cash in on this...

[ronaldbegg]

I will book mark this thread for future reference.

[SnapdragonGT]

As several others have said, this should be made into a sticky, well done for the write up 1955diesel, and also for your contributions, John.

I'll contact admin and see if they can do it, as having a quick ref guide like this would potentially save a lot of worried owners from having to post threads with their concerns.

Excellent!

[atoms]

Excellent, clearly laid out description of the HGF symptoms, I would also like to see this as a sticky.

A similiar one on VVC camshaft failure symptoms in a similiar vein would also be good. I guess the belt failre symptoms are clear enough

Thanks 1955 Diesel

Alan