MCCK gen spark plugs

[Bob Giaier]

I ran my generator a few times this summer for the first time in a very long time. I see a lot of white smoke and am thinking a head gasket could be leaking coolant into the cylinder. I've ordered new head gaskets and plan to pull the heads in a few weeks.

My question is how does one remove the plug wires? The spark plug cable look like it screws onto the spark plug. I really don't want to wreck the cables removing them. Can someone describe how the connection to the spark plug works and how you remove it. Sounds like a dumb question, but I guess I'm asking it.

[horhay1946]

You just unscrew the plug wire. That type of wire and plug is used on aircraft engines. If there is some rust you may want to use some PB Blaster or other type of rust pentrenate

[larryeddington]

Be gentle with them new wires are quite spendy to replace with the sealed ones.

[Big D]

After you uncrew the sleeve, pull the sleeve only back and then gently wiggle the end of the wire off the plug by grabbing the rubber end only, don't pull on the wire.

[Bob Giaier]

Got it, so the outer sleeve is a shield with an inner wire is attached to the spark plug. I'll be gentle. Thx

[Big D]

There are a couple of variations but these will give you an idea of what the ends look like:
http://www.ebay.ca/itm/MILITARY-GENERAT ... 0878125786
http://www.ebay.ca/itm/167-1432-ONAN-SH ... 20bd83e04d

[Bob Giaier]

I see. pricy too. Thank you

[Bob Giaier]

I just pulled the heads yesterday. The spark plug wires came off with no problem. Several water jackets in both heads were plugged and so was a re circulation port at both thermostats. It looks like black crust (probably rust). Anyways, I cleaned it all out. This things going to run beautifully now.

I have a complete manual, but it doesn't state anywhere what the torque is for the head bolts. Does anyone know what the torque is for these cylinder head bolts?

[Big D]

I have 29-31 ft lbs for the "cylinder head capscrews" Do you have the proper bolt tightening sequence?

[Bob Giaier]

Thank you. I don't have a torque pattern. I was just going to go to the opposite bolt (zig zag). Do you have something you can describe?

[Bob Giaier]

I've done some checking thru different internet sites one called twins lean.net has every manual Onan ever made. Anyways, the toque pattern is typical for other cylinder heads in that you start in the middle and criss cross to the upper end and then lower end, kind of like a rolling pin effect. I also see postings where it's recommended to do a re torque after an initial run.

[Big D]

The order is:
- second one down from the top on the right
- second one down from the top on the left
- third one down from the top on the left
- third one down from the top on the right
- bottom left
- bottom right
- top right
- top left
- top middle

[Bob Giaier]

Perfect. Thank you Big D

[Bob Giaier]

I do have one more question. The plug wires have tiny spring on the end that pushes against the spark plug contact. I'd like to put a little dielectric grease on the spring and contact. Not just for conductivity but I thought it might help with oxidation that I see on the spring. What do you you think?

[Paul]

I do have one more question. The plug wires have tiny spring on the end that pushes against the spark plug contact. I'd like to put a little dielectric grease on the spring and contact. Not just for conductivity but I thought it might help with oxidation that I see on the spring. What do you you think?

Absolutely!