Ford 851 Rebuild problems

OldMFGuy

New User
I have a Ford 851 Gas with the 172cid engine.

I got it cheap because the engine had give out (Camshaft Gear broke)

Anyway, Sent the block, crank shaft and heads out for machining. New sleeves, pistons, valves, guides, camshaft, lifters, pushrods, bearings, all of it new. pastigauged the bearings and all are .002" everything went together great. Oil pressure is around 50 PSI and runs smooth when I first started it. Too good to be true lol.

Anyway as I was getting things tuned in and valve lash done, it made a screeching noise and stopped pretty abruptly. I took out the plugs and could still turn the engine over by hand so I pushed the clutch in and held it down with a piece of wood and a clamp. and started it back up and it ran fine.

fast forward, to a few days ago. I was finally ready to try the thing out so I started it up, let it run at about 1000 rpm for a couple minutes put it in gear and drove around the yard and it did the same thing. a squeal and then abruptly stops running.

I just got down taking the head off, checking all that no issues or out of round or signs of damage in the top end. So I took the pan off and checked each rod bearing and they are all just like new (which they are). I only looked at the main bearing with the caps still on and none of them look like they spun in the journals.

I am at a loss, do I tear the engine down or could this be something in the clutch which i did not replace because the previous owner did it less than a year ago with receipts.
 

And I forgot to mention that in between the first instance and the second instance, I ran it for a total of around 40 minutes probably at intervals of no more than 10 minutes a time with the clutch pushed in with the board and clamp. with no issues.

Even though the temp gauge stays within the normal range I am going to get a temp gun and check it that way too.
 
Maybe some damage to your hydraulic pump. May have been the original cause of camshaft failure.
 
Engine noises are hard to diagnose unless you are standing in front of the noise maker. When you say [b:c19931c80a]screeching noise[/b:c19931c80a], the only thing that comes to mind is the fan belt?
 
Just like cdmn, I would go backwards..
And ask my self "Why did the Camshaft Gear brake in the first place?"
Those gears are pretty big, they dont "just break". Something is sticking when it gets a little warm. Or is poorly oiled..
 
I went through the hydraulic pump and replaced the gear, pump shaft and bearing.

I'm going to pull the top cover off the transmission case tonight and see if there is anything, like a broken tooth that is binding things up
 
A screeching noise and stopping abruptly sounds an awful like a warmed up piston sticking in a too small of a sleeve. Should see evidence from the top and bottom side, piston skirt side, scratches on the sleeve.
 
I would agree but the pistons and sleeves are new and I measured them along with ring end gaps, etc during the rebuild. Also after it did it the first time I pulled the head and re-checked all the measurements and the cylinder bores and there was zero signs of that.
 
Are you getting oil to the valve train? Did you check the plate behind the cam gear? I think it holds the cam in position. We had one break before. If you dont have your hood on you can lift your steering box up some to look at the clutch. You can also see a little through the tranny weephole plate. New inspection cameras are pretty reasonable now. Did you torque the flywheel down.? It runs pretty close to the bellhousing.
 
Yes oil to the valve train and while I was rebuilding the hydraulic pump I had made sure oil was getting to the back cam gear that drives it. All the gears are new and torqued to spec. I did torque the flywheel and ordered a camera from eBay this morning :)

I think I might be splitting this thing again :-(
 

It's a remote chance but I'd take the fan belt off and run it like that until the temps get a little warm.
You could have a water pump or generator trying to lock up.
 
The water pump is new and it has an alternator but I will try that next week. I'm going to wait for the inspection camera.
 
So if everything else checks out...a long shot. I bought a project tractor; the hydraulic pump was hammered. Rebuilt it, changed the all the fluids in the tractor. Went into the engine and and the timing gears were beat in a regular pattern. Replaced the gears. Split the tractor between the transmission and the hydraulic and the hydraulic compartment was full of pump pieces. Might want to go into the hydraulic compartment from the top (fill opening) with a magnet and see if you catch anything.

If the generator or water pump were seizing you should be able to find a hot bearing.
 
My brothers 800 does the same thing. I built a 172 diesel engine. When we put the engine in we put a lpto
5 speed. If run hard for twenty minutes it will squeal as it abruptly stops. Sounds exactly like it
seized up. You can immediately restart it and go again. It doesn't get used often and has been doing it
for three years. No idea what it is. I just figured one day it will be very evident what is causing the
problem.
Ron
 
update......

I brought someone over to help me with checking timing etc. It is not screatching. the ignition timing is jumping around a lot. it only happens when I am above 1200 rpm (at least so far) and i can start it right back up after this happens and it runs fine. when it starts to happen, you hear almost an ignition knock. the weights on the distributor seem to stick a little too and i pulled the distributor and it does have some up and down and side play.

thoughts?
 

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