There is a lot of discussion about the vunerability of the K series head gasket, from Lotus owners to MGF owners but how bad is the problem? What actually causes the head gasket to fail so often? Is the problem evident with all the engines or does it seem to affect some more than others? (I notice that some postings suggest failures as early as 800miles!). If a head gasket does fail, how involved is the repair job? Is it expensive? Will the use of a competition head gasket help prevent the problem? [image]http://www.exiges.com/ubb/NonCGI/images/icons/confused.gif[/image]
As far as I can recall, we’ve only heard of one Exige head gasket failure on this bbs.Don’t know for sure, bur as the Exige has the VHPD, I guess that an uprated gasket is used along the other uprated internals.No doubt someone will be able to comment with the facts.
Afraid not…it’s a standard Rover gasket. Head gasket problems are common, particually if the engine spends it’s life at high RPM.
Actually spending it’s life at high rpms will not cause a HGF, the primary cause is the cooling system, remember these engines were designed to fit at the front of a car where lots of air can pass over it and have low capacity cooling systems.One of the causes of HGF is the heat up, cool down cycle generated by the cooling system, the engine starts and the water around it starts to get hot, thermo opens, and lets litres of cold water rush into the engine and cools it down very quickly, thermo closes because of temp drop, same cycle happens all over again, its this that causes the majority of HGF (thermal shock) not high rpms, up there the water temp is high but stable.
Not on the K series! I agree that head gaskets can fail due to thermal shock but all manufactures test for this taking the engine from +100 deg to normally just below freezing, which is much more severe than anything your car can through at it. On the K series it is not normally the gasket itself which fails but is the joint with the head. At high rpm the liners vibrate, distort and move about which causes the gasket to “shuffle” about and damage the head surface. Replacing the head gasket only provides a temporary cure as it is the head surface that suffers. I have seen loads of K-series head gasket failures where there is no visible damage to the head gasket! This shuffling is quite common with metal head gaskets but is considered an acceptable price to pay for ease of manufacturer and sealing properties.
Not forgetting that the k was designed for a front engined installation. The thermal shock phenomenon is peculiar to the mid engine application. Its even worse in the MGF as the cooling is even more marginal.Having had an HGF and researched them quite thoroughly, the major contibutor is the cooling, not the revs. Revs of course can cause HGF’s , but IME it is not the primary cause in the ‘K’.The Elise does have a wonderful failure pattern, which has effected many. The coolant hoses on the front rad are not the most secure. Its faily common to have one of these pop off and a corresponding increase in engine temp. You’ll then often get an HGF a month or two later.CheersChris
Did Lotus ever have an upgrade for the head gasket? I ask becuase I just looked at an Exige post HGF (7k repair apparently ), and I wondered whether there was an upgrade which could have been put in?
Not forgetting that the k was designed for a front engined installation. The thermal shock phenomenon is peculiar to the mid engine application. Its even worse in the MGF as the cooling is even more marginal.
Having had an HGF and researched them quite thoroughly, the major contibutor is the cooling, not the revs. Revs of course can cause HGF’s , but IME it is not the primary cause in the ‘K’.
The Elise does have a wonderful failure pattern, which has effected many. The coolant hoses on the front rad are not the most secure. Its faily common to have one of these pop off and a corresponding increase in engine temp. You’ll then often get an HGF a month or two later.
Be careful blaming HGF on coolant hoses coming off, thats more likely an effect as opposed to a cause. Often HGF will cause the water system to pressurise and you will get hoses popping off, burst rads etc.
I may be wrong ,the early K series had plastic dowels in the head which wore and allowed movement and hgf.when replaced with metal ones I think the problem was pretty much sorted?
The problem is far from sorted, mainly because there are so many things that can contribute to failure.
i) thermal conditions, mainly addressed by remote thermostat
ii) head shuffle, mainly addressed by metal dowels
iii) poor adhesion of water sealing bead, mainly fixed
iv) low/uneven liner protrusion… still very prevalent, partial fix after failure by hand modifying gasket
v) head porosity… still very prevalent
vi) head softening and gasket dig-in… very prevalent
Gasket failure is very common on VHPD engines just as it is on regular K’s , engine which generate a lot of heat tend to suffer more with head annealing/softening if they are not allowed to heat up/ coll down carefully.
The only ‘heavy duty’ gasket available had a different method of bonding on the water seal, thus addressing one type of failure. The latest Rover/Payen gaskets are as good as they get.
Dave & Simon
Very much appreciated summary from you both.
Have you been using the same RR as Joe McCarthy?
SO you are on about that Adrian Newey car then… bet its really bloody reliable, Im sure he can run 400bhp all day long.
Im not aware that its me that comes out looking like a fool in these discussions Simon…
More of these mystery cars that race all day long with no issues. Can’t wait for you to spill the beans and let us all know who ownes all these wonderful machines.
C’mon guys, less scrapping, more watching Le Man/BTCC/driving Loti!
Well done Judd for finally getting an engine to last 24 hrs!