Crossflow Engine Problem

[Jambob144]

Hi everyone,

I was giving the engine some beans at a set of traffic lights- I spun the rear tyres up, then all of a sudden the tyres gripped a little then the engine cut out. The engine then turned over really fast as if there was no compression.

I then did a compression test and found number 2 was around half of the others.

I stripped the head off and found a slight score whereby my thumb nail just nicked it. I also found a score on cylinder 3 a similar size to this one. - I've got the piston out no damage to the rings.

Today I've removed the valves and it seemed number 2 was a little dirty, but not much more than the rest, so i have grinded all the valves back in.

I wouldn't have though these 2 things would have halved the compression?

Any ideas?

Cheers

[Forest_rallying]

You don't appear to have given us much information to how the engine ran after your initial problem or if at all.

Your loss of compression can only going one of three places, past the rings into the sump, a lump blown out of the head gasket or badly seating valves maybe due to one possibly being bent.

As for the slight score you have on two cylinders it's difficult to say without seeing photos of it. You don't say where the score marks are,bore , piston or head. Are all the rings free in the pistons?

[Jambob144]

Sorry for the lack of info.

After my initial problem, the engine turned over really fast as if there was no compression. But didn't start (engine was hot). I foolishly didn't check if there was a spark.


The score is around 30mm long at the top of the bore at cylinder 2. I've checked the valves and they look straight.

All of the rings are free in the piston, maybe of the rings aligned with each other lol?

[Graham]

the score is unlikely to loose you that much compression, it also doesnt explain why it wouldnt start, the engine would of started on only 3 cylinders so your probably looking in the wrong place, has the timing chain broken?

[Jambob144]

Thanks Graham,

I thought that would be the case. The timing chain is in tact. I'm going to have the cam out tonight and take a look.

I wonder if the low compression was a side issue and the electronic ignition has burned out.

Cheers

Jamie