Starting/running problem.

[JimX]

I know I've read a thread similar to this before, but I've done a few searches and can't find it.

I went to start the car this morning and it spun faster than normal, like it had lost compression or something. It took forever to start, so I charged the battery in case that was the cause (it wasn't). When it finally started it seemed to run ok. But there was a moderately loud knocking noise coming from the front, which made idling a bit more difficult (but not impossible). I pulled off the CAS to see if the cam gear had moved, but it's still ok.

I'm not really sure where the noise was coming from but it sounded like it could have been the water pump. But I checked both coolant and oil and they were still 100% ok (ie no loss and no mixing). Oil catch can is empty, with very little residue coming out of the vent. Apart from this noise and the interfering with idling, it seems like the engine is ok but I'm not sure.

I hadn't been thrashing it either. In fact the last time I drove it was to reverse out of the garage and back in again a few days ago, and it didn't have any problems starting then.

Anyone got any ideas of what this might be? I'm gonna take it to a mechanic on Wednesday, but if there's anything I can check in the meantime I will.

[JimX]

Blah. Well no one had any idea, but it's been fixed now at the workshop. I had a non-working lifter on the intake side which caused it to lose compression on startup. The noise was all in the valves when running. I take back what I've said previously about not needing an engine flush if running synthetic oil - my engine definitely DID need it. Since the flush it still has a faint noise, but it's at least working properly now.

The affected lifter may be worn which could have made the problem worse, but either way it was blocked and is now 10 times better than it was. I'm going to switch to Mobil 1 oil, which is meant to be the best type for preventing deposits (as well as all the other stuff it's meant to be good for).

[benm]

I take back what I've said previously about not needing an engine flush if running synthetic oil - my engine definitely DID need it.

More info ?

[JimX]

Synthetic oil contains detergents which are meant to clean your oil galleries and keep them clean. Obviously the oils I had been using (Motul and Castrol) did not do a good job of this. Mobil 1 has the best reputation for keeping your engine clean so I am going to switch to it.

The lifter could still be on its way out and I could get the same problem again soon despite having a clean engine, but at least by running Mobil 1 I can largely rule out engine deposits.

The advice here is if you are starting to get noisy lifters, the first thing to do is do an engine flush and put in some valve lube stuff (buy it from Auto 1 or the like).