641 in frame rebuild question

BILLBENDER · Jul 10, 2017

I have decided that I'm going to have to dive into my motor. It starts and runs good but when you put it under a load it loses all power and starts smoking badly. My question is how difficult is an in frame rebuild? I have never rebuilt one so just didn't know the difficulty. Any pointers would help.

Larry NCKS · Jul 10, 2017

What diagnostics have you done to arrive at the need to rebuild your engine?

Is your air cleaner clean? I don't mean just the oil sump. Pull the air cleaner hose off the carb. Put it under the same load. Does it still smoke badly?

The engine basically is the frame on that tractor. I guess one could do an overhaul without removing the engine, but you'd be hard put to service cam bearings. Besides that I don't believe you'd save yourself any labor.

BILLBENDER · Jul 10, 2017

I have pulled and cleaned the air cleaner and carb. Ran compression and while the numbers were good 118-125 one cylinder was around 105. After running cylinders 1 &4 the sparks plugs are wet with oil while the other 2 are fine. Haven't pulled air hose off carb but will tonight. I was asking about in frame because I saw it was an option for this tractor on this site. I just didn't know of anyone had any luck doing it that way. I don't have much engine experience so I thought I'd ask.

Welding man · Jul 10, 2017

I have ranted on this too many times,probably. We rebuild engines for a living . I have 5
in the shop now. We do not do in frame rebuilds,period. Too hard to check the crank,replace
the seals.Sleeves are much easier to replace out of the tractor. What about the
gears,camshaft etc. An in frame rebuild is a job half done,I don't care who does it. If you
want to hone the cylinders and put a set of rings and rod bearings in it you will end up
with just what you paid for. A half of a job for half of the money.That's your choice and
now I will shut up.

BILLBENDER · Jul 10, 2017

(quoted from post at 08:31:34 07/10/17) I have ranted on this too many times,probably. We rebuild engines for a living . I have 5
in the shop now. We do not do in frame rebuilds,period. Too hard to check the crank,replace
the seals.Sleeves are much easier to replace out of the tractor. What about the
gears,camshaft etc. An in frame rebuild is a job half done,I don't care who does it. If you
want to hone the cylinders and put a set of rings and rod bearings in it you will end up
with just what you paid for. A half of a job for half of the money.That's your choice and
now I will shut up.

Thank you for your input. That is why I asked.

old · Jul 10, 2017

In frame rebuild is a good way to end up with a block with a hole in it. Unless your set up to Mike each and every wear point of the crank shaft you do not know if your putting good on bad which can/will lead to big problems down the road. Only engines I have ever seen that a true in frame rebuild held up was the big diesel engine in the over the road trucks and even then you Miked the crank to make sure it was good before putting in new parts.

If your going to rebuild and engine pull the engine out have the block checked and dipped to clean it have the crank checked and turned if needed and have the head rebuild by a good machine shop

WayneIA · Jul 10, 2017

When did Ford put cam bearings in there gas tractor engines?

souNdguy · Jul 10, 2017

i'd do a wet / dry compression test on her first. see what you have. never know.. might just be top end head work..

BILLBENDER · Jul 10, 2017

(quoted from post at 12:21:26 07/10/17) i'd do a wet / dry compression test on her first. see what you have. never know.. might just be top end head work..

What exactly would o be looking for on a wet dry test? The compression I did was first on a cold engine and then on a hot engine. I didn't do a wet test though.

old · Jul 10, 2017

A wet test sort of seals things that are leaking like valves that may not be set as they should be or rings not sealing like they once did

sunbeam · Jul 10, 2017

You might try just replaceing valve stem seals especially if it smokes more at an idle.

showcrop · Jul 10, 2017

Certain parts of the job are so much easier with the engine upside down on a stand, that it makes the work to remove it insignificant.

mmfan55 · Jul 10, 2017

I would start (after the testing
already stated) at pulling the head
and having a good machine shop check
it out. You will want to do that
anyway if you overhaul: but you may
find your biggest problem may be
badly worn valve guides or valve
stems. With the head off: you can
see how much ring groove is in the
cylinders and feel how loose (or
tight) the pistons are in the bore.
With it running okay until it gets a
load, a good head rebuild may fix you
up for a good while.

Ultradog MN · Jul 11, 2017

Not sure when but all 65 and newer have them.
I just replaced a set on a 3 cyl.

markct · Jul 11, 2017

Everyone I ever opened had bushings the camshaft ran in

Destroked 450 · Jul 11, 2017

On the early 4 cylinder engines the cam ran in the block, Ford started using cam bearings in the 65-later engines.

riveroadrat · Jul 16, 2017

(quoted from post at 19:09:59 07/10/17) When did Ford put cam bearings in there gas tractor engines?

I also thought they didnt have cam bearings. The first time I helped my father rebuild a diesel I said to him that there werent any cam bearings. The cam journals are very large though.

641 in frame rebuild question

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