1949 Merc 8CM engine
 

Hello, My son got me a Merc 8CM engine that I want to put it in a 40 Ford cpe,It is stuck/frozen and missing parts. I have it cleaned up on the outside and would like to have some suggestions on how to get it unstuck. I was told it was sitting a longtime in a dry garage. Thank you Tom Z...

Re: 1949 Merc 8CM engine
 

Fill cylinders & intake ports with diesel and let it sit for a couple of weeks. Now with 12 bolts to starter only hit it. It will will either come free or break ring gear. No biggie if it breaks ring gear as if its that stuck it will have to come apart anyways. You can do this with engine sitting on ground. Cover engine with one sheet or something as if it comes free it’s going to spray diesel everywhere. I put 40,000 on one after freeing it up this way.

Re: 1949 Merc 8CM engine
 

I'd use some 50/50 mix to free up the cylinders. However you might have some stuck valves, and their a bugger to get loose.
Gramps

Re: 1949 Merc 8CM engine
 

Why not take the darn thing apart, figure out WHY and WHERE it is stuck and do it properly? It might only cost you a gasket set (which isn't a bad idea anyway) and you'll know what you have.

I'm just not a believer in throwing an unknown engine, with unknown potential problems into a car . . . when the engine is already out of a car and can be properly inspected, cleaned up and fixed. Heck, it might only need some good cleaning/polishing and some new gaskets . . . or it may need a LOT more and trying to "unstick it" may do more harm than good.

Also, as it is a used engine, who knows what is lurking in the oil-pan, the oil-pump, in the valley, etc.. Think about all the crap that can be (and usually is) inside an old 50's engine (non-detergent oil days) . . . just waiting for you to "unstick it" and then it can pump through your bearings and really ruin the lower end.

Take it apart! Whew . . . time for bed . . . my 3 cents!

Re: 1949 Merc 8CM engine
 

Yes, take it apart.My french flathead came with only 600 hours on the counter after being completely overhauled in Clermont-Ferrant where all french flattys were repaired for the french militair. I took it apart and found the sludge traps inside the big ends half full of crap, all valves needed a bit of grinding to regain proper seats as well. Cleaned the water jackets out and made sure the internals are spotless before reassembly.The reward is now a cool running and complete oiltight engine were I know everything inside is in good order. It did cost me just a gasket set and I had to make new bungs for the crank - nothing else was needed except a bit of paint to make it look nice.

Re: 1949 Merc 8CM engine
 

I'm with the "take it apart first" crowd. There's a Merc crank in there, so I'd be extra careful.

Re: 1949 Merc 8CM engine
 

Even if you freed it up I vote for taking it apart, cheap insurance.

Re: 1949 Merc 8CM engine
 

It could be very light corrosion causing stuck pistons or valves or it can be heavy corrosion on one or more cylinder walls that will require cutting some pistons out. It just depends on how and where it was stored.

I'd pull the heads and manifold minimum to look for corrosion or mouse nests in the valve chamber. You never know what is lurking around in there without visually inspecting it. Mice can get through some pretty tight spaces and corrosion can come from humid air.

Re: 1949 Merc 8CM engine
 

Thank you so much for the good advice on the Merc 8CM engine. I will pull the intake & the heads to see what could find. Hoping not to break any bolts or find any cracks. I will post my finds. Thanks again Tom Z...

Re: 1949 Merc 8CM engine
 

When you get it apart and it's just the pistons stuck in the bore, mix up a bottle Acetone and ATF, 50-50 and put an inch or so on top of each piston and let it sit a week or so, topping up as required. If you can get it on an engine stand rotate it so the piston tops are level and do each bank separately.

cheers