Follow-up on the hard start problem.

[troylatif]

Okay, I figured it out. Thanks to the gentleman who posted to my last thread. It was a compression problem. I seemed to have a bent intake valve coupled with a bad exhaust valve on another cylinder.

So, I got two new valves, installed them, and dropped it in. Before I put in the rocker arms, it gave consistent compression across all six cylinders.

Now, I was really careful when prising the springs to drop the rockers back in, but somehow I bent another four exhaust valves. Not big bends, but slight ones that'll develop a loss in power. Is it a big problem that I'm not using the MB recommended tool?

Also, just a sanity check, but when pressing valves, that should be done with the piston at bottom dead center right?

Thanks guys,

-Troy

 

[troylatif]

Oh, another question. What should be the pressure reading when compression testing with a remote starter? I get roughly 60 psi at best from a good cylinder. Is that enough?

Thanks again,

-Troy

 

[Ultymate]

Troy you don't say whether your car is petrol or diesel but either way 60psi is useless. Also I can't understand how you can fit vaves without removing the cylinder head(s), it's a physical impossibility.:-?

 

[troylatif]

well the engine is petrol. I've found in a manual that the minimum is something like 8.5 bar which is close to 126 psi.

This confuses me because I've checked the piston to wall clearances and rehoned the block with new rings etc. I get about a 0.15 mm gap between piston and wall at the topAlso, the valve seats have been reground and by now most of the valves are new.

Any ideas?

Thanks,

-Troy

 

[panason1c]

somehow I bent another four exhaust valves. Not big bends, but slight ones that'll develop a loss in power.

Is it a big problem that I'm not using the MB recommended tool?..........

when pressing valves, that should be done with the piston at bottom dead center right?

With respect, i suggest you need to have an experienced mechanic to look at it. :-?

 

[Bolide]

Ask yourself one question: why are the valves bent?

Nick Froome
www.w124.co.uk

 

[troylatif]

Well, I had come to the conclusion that I had been installing the rocker arms incorrectly. That was the first time I found bent valves causing low compression. Then I replaced those. I reinstalled the head. This time, I did the same old screw driver against the cam post to lever down the valves while pushing in the rocker arms. Again, I got a slight leak out of the cylinder head. So I remove the head... again. and I find another four exhaust valves just so slightly bent that you can see daylight through the port.

I put in an order for those four and the special tool to depress the valve springs. Do you think that'd do it?

-Troy

 

[BlackC55]

I think the timing maybe out.

Check the chain and make sure its timed up properly.

 

[troylatif]

With regard to the timing chain; I'm almost certain it was timed properly. The chain is new. Before these cyl. leak issues It was turning over the timing marks right on the dot. I was rather meticulous about getting the timing marks to be within micrometers of one another.

Going back to the cylinder wall clearance issue. Does anyone know what the wall to piston clearance should be for the m110 engine?

Thanks,

-Troy

 

[sweeper]

Firstly, i congratulate you on having a go, when removing valves you should support the valve head when compressing the spring although it is difficult to see what you did to bend the valve, maybe you did it fitting the rocker arms. you cannot do a compression check without the rockers fitted as no air will be drawn in. a compression check should be done a working temp. with throttle held wide open, depending upon engine expect readings to be within 10% of each other and around 150-220psi.

 

[hmang]

With regard to the timing chain; I'm almost certain it was timed properly. The chain is new. Before these cyl. leak issues It was turning over the timing marks right on the dot. I was rather meticulous about getting the timing marks to be within micrometers of one another.

Going back to the cylinder wall clearance issue. Does anyone know what the wall to piston clearance should be for the m110 engine?

Thanks,

-Troy

piston - wall clearance is measured at the lower section of the piston.

pistons are tapered...fat at bottom thin at top to allow for heat expansion.

i would not be worrying about pistons at this stage

 

[troylatif]

Thanks for your replies and input.

I currenly have the head up on a rope hanging from my engine crane. I'm waiting on the valves and the special compressor tool. I'll definitely get it to idle first before the compression test.


Thanks again,

-Troy