You may remember that I overheated the engine (351W) on my '82 when pulling a trailer loaded w/another '82 that's to be a donor truck. As discussed on another thread, the tests indicate that I have a coolant leak somewhere inside the engine. Obviously I have to pull the heads, and I'll send them out for pressure testing and replace the head gaskets. And I plan to pull the engine to facilitate doing that, but the question becomes how far to go with work on the engine.

One issue that has me concerned is the speed with which the engine overheated. The temp went up rapidly while on the highway on a fairly cool day. The water pump is new, as is the radiator cap, thermostat (180), and coolant. I've read that it isn't unusual for the water jackets to filled with junk, so maybe I should pull the freeze plugs and check that out?

Also, I have a rear main leaking a bit, so could roll the engine over on the stand and replace the seal. (I'm assuming it'd be a lot easier to do on an engine stand than in the vehicle - even though I have a lift.) And, while I have the pan off should I pull the rod and main caps, one at a time, to check clearances?

On top of that, a professional mechanic suggested that I might have taken the temper out of the rings when I overheated it, so he'd recommend pulling the pistons, honing the cylinders, and replacing the rings. But, if I've taken it that far down should I have it bored and, while the block is at the machine shop, have it checked for cracks - since I don't really know that the current leak is head gasket and/or heads.

As you can read/see, I'm struggling with just how far to go. But, I want the truck to be reliable when I get it back together, and that would include towing w/o overheating. THOUGHTS?

 

If I were you and had to tear it all down I would build it back together hopped up. It may cost more, but if you are pulling the heads and pistons why not?

 

It depends on how much you want to spend... I had 1200 bucks into the machine work on my 400, plus had to replace just about everything. The only thing i didn't replace is the rods and the block...

I personally think if you are going down that far, you should get machine work don't one it. But if you don't want to spend a whole lot, I would just clean it real good and buy a rebuild kit...

 

You would not necessarily need to bore it, you will have to measure it to see what you have. I believe .006 is near the limit for a re-ring job that will hold for awhile. You can somewhat tell by how much of a ridge there is on top of the cylinders. If it's a very large ridge, you are going to have to get that cut out before you can get the piston out. And that would be a bad sign and it would need boring and new pistons.

You may find the engine is in good shape, only needing re-ringing. I would definitely change the timing chain and gears if you do nothing else.

Go buy the book "How to rebuild your small block Ford". It's worth every penny you spend on it and will guide you through the whole process..

 

Gary, if you are pulling the engine out for the head R&R, and replacing the rear main seal while it's out, I'd say go ahead and check the rod/main bearings (you're gonna have 1 main bearing apart anyways). If the bearings have a little wear, it might be a good idea to go ahead and give the engine a complete freshening up.
If you haven't already replaced the timing chain (IIRC you replaced the cam already) now would be a good time to do so. Same for the oil pump. Check the pickup screen, if in doubt, replace.
Yeah, it will cost a bit more than simply repairing the heads, but if plan to keep the truck, it'll pay off in the long run.

 

Thanks for the thoughts, and here are mine with regard to yours:

• Glove: I've already hopped it up a tad w/a Comp Cams bump stick - the XE250H. The off-idle response is excellent and it towed the car-hauler trailer very well. And, until it overheated it was doing well w/the twin truck on the trailer. But, I'm thinking about going w/a 4 bbl and manifold - probably the Edelbrock Performer manifold awa their AVS-based carb.
• '80: I really didn't want to spend anything, but must so will keep it as minimal as is reasonable. Yes, if money weren't an issue I'd bore w/a deck plate, align hone the crank, resize the rods, and balance it. But, since I'll probably sell this one when I get Dad's '81 done, it seems prudent to keep the costs low. Refresh is sounding better.
• Franklin: I have the "How to rebuild your small block Ford" book and agree it is worth every penny. IIRC from my previous pull-the-heads project, the ridge isn't much. But, I have a ridge reamer so that's no prob. And, I have snap gauges and mikes, so can/will check to bore awa pistons out. But, will probably use Plastigage on the rods/mains. And, as RW recalls, I have replaced the timing chain set.
• RW: Even if not keeping the truck I do want it to be reliable. So, assuming the bearings and crank are in good shape and the piston/bore clearances are w/i tolerance, it is sounding like an oil pump and rings might be the low-buck ticket. And, even if the bearings are loose, I could probably replace them w/o turning the crank.

Thanks to all for helping me think through this. And, if you have more comments I welcome them!

 

Gary, even if the bearings are a tad loose, don't forget that you can get .001-.003 oversize bearings as needed to make the clearance tighter and closer to spec. That's one advantage of having a crank that has not been ground. Once the crank has been ground .010 or more, bearings only come in the standard oversize increments.

 

RW - Good point. Maybe she'll just need new bearings and rings. And, I'm hoping to do the hone work myself, though I've not done anything bigger than a Model N Briggs. But, should be the same with a bigger hone.