M2 Halftrack
yd328160ax
Hi Karl, I'm getting to the point of doing work on my motor and looking for some advice. Can you tell me about your in-frame, what you did etc. ? My motor seems to run good, but I do have some blow-by.
Thanks Gary
Hello Gary,
These motors are very easy to rebuild and all parts are available. The original motor ran great when purchased and I debated to rebuild or not, glad I did, found a broken piston ring. I wanted to rebuild ours in the frame before removing, that way I could run it in and work out the bugs before reassembling the halftrack.
The only short cuts I took was not removing the crank and not re-boring the cylinders.
The crank bearings and main surfaces were fine and I did not want to mess with the wood stick rear seals. I did replace the connecting rod bearings. The pistons were 20 over already and had very little ridge on top. I replaced the original pistons with new ones and honed the cylinder walls. The one cylinder with the broken ring had some vertical lines that I could not hone out.
I purchased a set of new 20 rings, but found the ring gap spec was just under the max gap. Ended up hand fitting a set of 30 over rings on the new 20 over pistons.
Lapped the valves, replaced the exhaust valves, guides were OK, replaced all valve stem seals. Since the lifters are hydraulic, setting the valve gap is done by cutting the stems, only two of my new exhaust valves needed trimming.
Replaced oil pump, water pump, distributor, generator, thermostat, hoses, belts and all gaskets.
The oil pump was a pain, since it is turned by the cam shaft and the oil pump turns the distributor it has to go in correct. If wrong you have to drop the oil pan.
Only issue was a cracked head found after start up. I had the original head milled and mag fluxed, crack was not on the cylinder side but the top. A small crack was found at one of the thermostat housing bolt holes, may have been there or cracked during reassembly. Found a NOS head in a wooden crate for $100
Factory cylinder compression is 125 psi, after a half hour of run in ours was at 117-120 psi. Good enough for me and may improve once the rings set in. Original cylinder compression was 90-100 psi before rebuild. Oil pressure was 30psi. I'm happy with the results, since I only plan on driving this maybe 50 miles a year.
Get the TMs and call Gary's Halftrack Parts for all your needs and advice.
Let me know if I can be of any help.
Karl
