743 head gasket/head replacement

[Billybobjoe12323]

Hello, I'm tearing apart my v1702 engine in my bobcat for the first time and was looking for some advice. It was overheating constantly and then finally it blew the dipstick out of the block along with a bunch of oil.

I was able to limp it into my c-can and get the head off. I found some water on top of one of the cylinders and some damage to what I believe is the pre-combustion channels on the head, I will attach pictures for reference.

I'm wondering if a machine shop would be able to fix the head or if it's too far gone?

Also I heard you can check if your rings are good by pouring oil on top of the piston to see if it leaks down or not. Is this a valid test?

What else should I do while I have it apart?
And what else should I be looking for? The cylinder walls seem smooth from what I can tell, one has a slight lip near the top.

Should I also replace the injectors at the same time?
I also noticed alot of what seems like black silicone all over the gasket and block/head. is this normal break down of the head gasket or did someone try using rtv or something at some point?

Any help or advice would be awesome!

 

[Tazza]

Blowing the dip stick out is from crank case pressure, this is almost always due to rings not sealing the bores. You mentioned that you have had over heating issues, there is a good chance the rings have stuck in the ring grooves.

You are this deep, pull the sump, then the pistons. Check the rings are not stuck.

The cracks in the pre-coms is not unusual, they almost never crack too far and fall into the cylinder. We rebuild a hand full of these engines every week, and i think i have seen one fall in 3 years i have been there.

Check the groove from the pre-com to the valves for cracks, this is the most common area they go.

The oil in the cylinder trick is a wet test. When the head is on, pull an injector or glow plug measure the compression, then give it a squirt of oil and re-test. If it goes up it shows your rings are not sealing.

 

[Billybobjoe12323]

Thanks for the advise! Unfortunately I don't have an engine stand so wasn't able to pull the block out. I can't see any cracks just that damage to the pre-combustion channels. I'm assuming I'll still need to have the head machined before putting a new head gasket in? If I do that and re assemble the head could I do the compression test then to find out if my rings are shot?