Head gasket blown / sigma 120
Discussion
Hi everybody
I couldn't find anything about blown head gaskets in a sigma engined caterham, so I thought I'd write my experience for future reference. My 7 is a 4-year old sigma 120, factory built. I have tracked it extensively with no mechanical issues whatsoever. A year ago, I crashed it in traffic and had to fit a new nose. The radiator was hit, but my mechanic told me it was OK. I drove it about 30 to 40 times since the accident with no problems. It had it first MOT (passed with flying colors) one week before the last time I drove it, I did a 30 min spirited drive through mountain roads. Temps OK and no other problems.
After letting the car sit for 6 hours, I drove it home at about 65 mph on the highway. Then a whitish liquid came out of the engine into the windshield. Stopped at once. Tow trucked it to the mechanic and he just called telling me that I had a blown head gasket and that there was a bit of damage to the engine.
He said he couldn't find any obvious cause of trouble. He also told me there's a large build in my future :-(
I couldn't find anything about blown head gaskets in a sigma engined caterham, so I thought I'd write my experience for future reference. My 7 is a 4-year old sigma 120, factory built. I have tracked it extensively with no mechanical issues whatsoever. A year ago, I crashed it in traffic and had to fit a new nose. The radiator was hit, but my mechanic told me it was OK. I drove it about 30 to 40 times since the accident with no problems. It had it first MOT (passed with flying colors) one week before the last time I drove it, I did a 30 min spirited drive through mountain roads. Temps OK and no other problems.
After letting the car sit for 6 hours, I drove it home at about 65 mph on the highway. Then a whitish liquid came out of the engine into the windshield. Stopped at once. Tow trucked it to the mechanic and he just called telling me that I had a blown head gasket and that there was a bit of damage to the engine.
He said he couldn't find any obvious cause of trouble. He also told me there's a large build in my future :-(
You do not hear of many head gasket failure on Sigma engines. I think it is unlikely that the accident damage to the radiator had anything to do with it, unless it did cause it to over heat at some stage.
The 'white' liquid was probably an emulsion of oil and coolant mixed together. The question will be is whether it came form the coolant system, the oil breather, or the dipstick. From what your mechanic has said, I think it is likely that the oil has become contaminated and he is worried about possible damage to the bearings.
I personally would repair the gasket and change the oil a couple of times (to flush out any contamination) and if oil pressure is OK, leave it at that.
The 'white' liquid was probably an emulsion of oil and coolant mixed together. The question will be is whether it came form the coolant system, the oil breather, or the dipstick. From what your mechanic has said, I think it is likely that the oil has become contaminated and he is worried about possible damage to the bearings.
I personally would repair the gasket and change the oil a couple of times (to flush out any contamination) and if oil pressure is OK, leave it at that.
DCL said:
You do not hear of many head gasket failure on Sigma engines. I think it is unlikely that the accident damage to the radiator had anything to do with it, unless it did cause it to over heat at some stage.
The 'white' liquid was probably an emulsion of oil and coolant mixed together. The question will be is whether it came form the coolant system, the oil breather, or the dipstick. From what your mechanic has said, I think it is likely that the oil has become contaminated and he is worried about possible damage to the bearings.
I personally would repair the gasket and change the oil a couple of times (to flush out any contamination) and if oil pressure is OK, leave it at that.
I think that you will find the 'whitestuff' is called a colloid, in this case oil and water, it can happen with condensation but its unlikley in this instance, also it will be far better to change the gasket rather than try to repair it The 'white' liquid was probably an emulsion of oil and coolant mixed together. The question will be is whether it came form the coolant system, the oil breather, or the dipstick. From what your mechanic has said, I think it is likely that the oil has become contaminated and he is worried about possible damage to the bearings.
I personally would repair the gasket and change the oil a couple of times (to flush out any contamination) and if oil pressure is OK, leave it at that.
Get the head checked it may require a skim and whilst your at it get the bottom of the engine checked...yes those bearings, you know it makes sense.
But also is there a route cause ? it may be a simple head gasket failure, or is there something more and the Head gasket is just a symptom? also you may wish to consider new headbolts, waterpump and Cam belt I am sure others will be along shortly with wise words.
Sorry to hear of your problem, it certainly doesn't sound like you have abused the engine at all. How is your water pump? I'm servicing my car at the moment and noticed the pump seal is just starting to leak, my car is coming up to 3 years on the road, so similar age to yours. I had been told that they can fail quite early and it might have lead to your gasket failure.
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