The Stovebolt Site Forums The Shop Area Engine Shop Water pump pulley removal

Hi All,
I have a 53' GMC 1/2 ton, long bed. I do not know much about these old trucks, other than they're cool. We think it's a 248 engine. It's froze up, been soaking the cylinders in Mystery oil since Dec, while I installed new brakes, hubs, tires etc. We've tried prying on the flywheel, it won't move. The balancer I don't think is original to this truck, it has the notch for an old hand crank like on a Motel-T. Right now we can not get the pulley off the water pump, and of course there is mounting bolt right behind the edge of the pulley. It looks like someone broke off two top bolts in the pump, unless these are alignment pins? Is there jack screw holes that pop the pulley off or is pressed on? I can't imagine it's press on, because just us prying on it, started to bend it. Like I said I don't know a lot about these trucks or engines. I ask the guy I bought it from, his reply I can't remember. Does anyone know where, I could purchase a rebuilt engine and manual trans, or have mine rebuilt? Any help would greatly be appreciated

Engine displacement start of SN, stamped on machined pad, r side behind distr. I e. 248xxx.

Ed

The balancer should be a press fit on 248.

Post the numbers stamped on the boss low on the block between the dizzy and the starter.

Can't read the numbers.

The balancer isn't the big issue at the moment, The water pump and pulley are. The pulley will not come off the pump. There are either two broken bolts or two pins in the top of the water pump, can't remove the pulley to get to the bolt behind it, so I can remove the head.

I'm pretty sure none of the water pump bolts connect to the head. One of the water pump bolts (upper left when looking from the front) is "captive". It will not come all the way out of the pump without removing the pulley, but it can be unscrewed from the block without removing the pulley with an open end wrench. If you need a picture, I have one buried in a tub in the garage.

Like Joe's, my '52 GMC's balancer has the notches for a hand crank. You'd have to drill a hole through the bottom of the radiator to get the crank in place though.

JoeCole, IIRC, the pulley on that water pump is a "press fit" onto the shaft. There are only 4 bolts that mount the pump to the block and only one of those is partially covered by the pulley (left side of pump facing the front of the engine). There are 2 threaded bolt holes at the top side of the pump that may look like they are from broken off bolts, but those are where the water pump rear plate is secured to the face of the pump from the rear side.

If you have the 3 exposed pump mounting bolts removed, you should be able to slightly loosen the last one that is at about the 9 o'clock position, then pry the pump face loose from the block. An open end wrench is probably the only thing you will squeeze in there to begin that process.* Once the pump is loose, continue to loosen that last bolt while holding the loose pump until it comes out of the block. Your pump is now off the engine.

* You could grind down the thickness from a box end wrench to slip in between the gap and get a better grip on the bolt head if it's stubborn.

NOTE: Bill beat me to the punch on his reply. Will leave mine up as it has pictures that may help better visualize the solution.

As Bill Hanlon so correctly pointed out, you do not need to pull the water pump to take the head off the motor. The 4 bolts holding the water pump go into the block. They do not go into the water jacket so they should not be rusted in. The captive bolt originally had a slot in the head so that you could use a screw driver once you got it loosened. A combination open/box end wrench will get that bolt started. Do the other three first and the captive one last. You pull the pump away from the block as you unscrew the bolt. I would not recommend to take the pulley off. You will do more damage than help. Let the rebuilder worry about the pulley. Ask more questions as they come up. We are here to help.

Thanks to everyone who has replied, it's greatly appreciated! But, yes that is the bolt, I'll see if I can either grind down a wrench or get one from a friend. I tried to post a few photos but I can't get them to load. You're right, we've already put a dent in the pulley. If you could see the water pump, I am sure it isn't any good. Where do you guys buy new parts such as pumps? and is there a place that rebuilds these old motors and transmissions? Thanks again!

Once the pump is off, use a thin cutoff wheel on an angle grinder to cut the head off the bolt, and install a short stud in the block so a nut can be used instead of a bolt when it's reinstalled. problem solved!
Jerry

New parts are often worse than the old one you're replacing. It's all junk from China.

Your best bet is to rebuild your old pump or have it done by a place such as Then and Now Automotive www.then-now.com or The Flying Dutchman

Water pump rebuilder and seller of antique water pumps for all makes and models

Flying Dutchman
Wade Jenezon, 650 Upper River Rd
Gold Hill, OR 97525 USA
1-888-595-1110 Outside the U.S., 1-541-450-2277
http://water-pump-rebuilders.com/

You will most likely faint when you find out the cost of a rebuild. Maybe look around for a running motor that will drop in. 228,248,270 and 302 are the drop ins from cheapest to most expensive. You need to size the engine based on what your intended uses for the truck are. Then you will have to compromise to what your budget allows. Transmissions are readily available. Buy the stuff from somebody you trust or know. You could also ask on here if anyone has some to sell. A member here will not screw you and ruin their reputation on the site. You may have to make a road trip to pick up the items.

As for engine rebuilders, Jasper Engines will do it but I think they wanted about $7000 for the job.

Picture of my spare water pump from the engine side. The captive bolt is shown on the right. Mine has a slot in it. The bare steel is where the pump to block gasket goes.

Just make sure that whoever rebuilds the water pump puts the (hopefully slotted) bolt back in place before they put the pulley back on. That bolt is the kind of thing that gets misplaced in a shop.

Great Idea! Thanks!

Thanks! I'll keep that in mind.

I figured as much. I don't plan on putting a ton of money into the truck, The plan was to drive it old and worn just like it is. If I can find a drop in motor that would be great. I have a 327 small block with a 4 speed trans that came out of my 78 Malibu. worse case I'd drop that in there. The issue there is I want to keep the three on the tree. that's really the only thing I'm worried about keeping with the truck. But from what I understand a small block won't mount to the factory truck three speed. I'm not looking for any type of horse power I just want to drive the truck to and from work.

Thanks, $7k seems a bit high for a straight six to me, I'd be willing to go with around $4k though.

Thanks for the photo, that helps a lot actually. I took some photos of mine on the truck, but can't figure out how to insert them here..lol

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I'll make sure. Who rebuild yours pump or where did you buy it?

I've had two done at this place. First one was 10+ years and 40,000+ miles ago. Still working. They did it in a day, but I was a walk in customer with a stranded truck. The second pump is a spare or to be used on my 302 if I ever get around to putting it in the truck.

A 270 (and possibly a 248) can be fitted with slip-in flanged sleeves and pistons for a Nissan diesel forklift engine. I'm in the process of accumulating the parts for that conversion now, as well as increasing the stroke of the 248 engine by 3/8" by offset grinding the crankshaft. Connecting rod bearings for an Allis-Chalmers tractor engine can be used in that conversion, using original GMC connecting rods sleeved down to use the smaller diameter bearings. With the longer stroke the 270 becomes a 300 cubic inch engine, and 270 blocks are a lot easier to find than 302s.

The same piston/sleeve assemblies along with a 3/8 " stroke increase can make a Chevy 261 approach 300 cubic inches. That conversion uses rod bearings for a 2.4 liter Nissan 4 cylinder engine. All the above modifications fit INSIDE the engine while maintaining the original outside appearance. That's called a "sleeper" engine on the round track racing circuit.
Jerry

Joe, I came across 2 potential sources for rebuilt water pumps for your 248:

Dan's Classic WATER PUMP, REBUILT - GMC 228, 236, 248, 270, 302 w-7/8" pulley (I'm not associated with this vendor or have ever purchased from them)

Ebay seller offering a 1939-59 GMC Truck 10/35 228 248 270 I6 rebuilt water pump 598309 new 5/8" pulley (also not associated with this seller)

As an alternative, post an ad in the Truck Parts Wanted forum and see if there may be a fellow Bolter that has one you could purchase.

Thanks! I am sure mine is going to need rebuilt. I'm betting my engine will as well. I have another question as I want to drive this thing yesterday. There is a guy about 10 mins from my house selling a 250 that came out of a 64 Nova.it was a three speed car. The motor was rebuilt,he wants $500 for it. Will this fit right in my GMC and mount to the trans? My thoughts are I can get this, and get my truck rolling, then rebuild my engine and take my time with it. He needs the cash, and said if I take it, I can't bring it back, but he did say I could come there take photos, and turn it over, so i know it's not locked up. I was thinking about going to get it, and start the swap, since after tomorrow, I'm off work until next week. Sorry for so many questions, but this is all new to me. Thanks in advance.

Also thank you Hot Rod Lincoin for the info!

I'm pretty sure the largest six cylinder engine in a 64 Nova was a 230 cubic inch model. Not to say that someone couldn't have swapped a 250 into the Nova.

The Chevy bell housing should mate to the GMC trans.

The motor mounting arrangement is completely different, with 1 front mount and 2 side mounts on the GMC bellhousing vs. 2 side mounts on the 250 engine and the expectation of one transmission mount on the original Nova transmission. So with the Nova engine and the GMC tranny, there wouldn't be anything holding up the rear of the engine or the transmission.

Thanks! I won't waste his or my time then. What engines and years will direct swap or where can I find that info? I've been searching all day. I found another motor and trans, (three on the tree) the guy says it will fit right in my truck, but it also came out of a nova. He says he knows without a doubt it would fix, but will allow me to return it if it doesn't.

230 and 250 engines run the same engine block- - - -the difference in displacement is the crankshaft stroke length. Neither one will bolt into your truck without major modifications. A 1962-up V8 bellhousing and some front motor mount fabrication at a bare minimum, plus different radiator mounting and throttle linkage fabrication. Then the fan will run way too low on the radiator for efficient cooling.
Jerry

Thank you! You saved me a lot of time and money. Could you tell me what motors and what years I need look for, to do a direct bolt in? I've been searching but haven't came across any solid answers, folks keep suggesting I swap this or that. I keep telling them I want to keep the three on the tree. That's it. If I have to change that, then I'm not interested. But that falls on death's ears.

Thanks again!

"Maybe look around for a running motor that will drop in. 228,248,270 and 302 are the drop ins from cheapest to most expensive. You need to size the engine based on what your intended uses for the truck are."

Joe Cole, The path of least resistance would be finding a 56 or later 235. There are still lots around and many good ones got pulled in favor of small block V8s or 261s. The water pump location on the 55 2nd and later 235 isn't insurmountable and on a GMC you would have enough room for the 235 fan. On Chevs and probably GMCs, you need to drop the radiator in its mount a couple of inches so the lower hose clears the fan unless you use the available modified water pump mounting. But you can get by without that, I have for many years.

A 235 will bolt to your bell housing and so use the stock transmission. Parts for a 235 are cheaper and more readily available than for a GMC with the exception of camshafts blanks and for the 55 2nd and earlier 235, main bearings. So I would look for a 56 or later 235, Powerglide or stick, doesn't matter. Aside from moving the front motor mount back a couple of inches and the water pump, its a drop in .

Thanks! These are the only drop ins that will fit? I have folks trying to sell me 261 292 and something else. Telling me they will fit right in. I got the head off mine today it's locked up so tight, it's unreal. There is a shop in the next town, that said they can rebuild it for me, for $3000-5000

Thanks for the info. I'll definitely keep that in mind. I'd honestly rather not have to move anything to make the motor fit. I'd prefer a straight drop in, however if that's now possible, it's nice to have a back up plan.

The 235/261 engines are a couple of inches shorter than the GMC, so you'll have to do a little monkey motion on the front motor mount position. Other than that, and possibly a little tweaking on the exhaust pipe and throttle linkage, the Chevy engines will be the easiest to adapt. 250 and 292 sixes WILL NOT be an easy swap. One simple way to free up a badly locked engine is to use a big hole saw to cut the piston tops away just inside the rings, and break the centers out with a BFH and a chunk of round steel bar on the piston tops. They're going to be trash anyway, so there's no point in going to a lot of effort to save them. Nissan Diesel forklift pistons and sleeves can be adapted to a GMC engine instead of paying outrageous prices for custom made pistons.
Jerry

Thanks! I'd rather not, have to move or mess with anything. I just want a straight drop in motor. The problem I am having (besides finding a running motor) is I have all these folks emailing me and messaging me on FB and everyone is contradicting each other. It's enough to drive you nuts..lol. There is a guy that has a 216 he said came out of a 48' chevy, He says it will fit. Another guy says the 235 is the 216 with a few more HP, and that a 235 won't bolt right in, without moving mounts and or the rad. Therefore I have to assume the same for the 216?

Are these the ONLY engine that will bolt right in 228,248,270 and 302 ? If so does anyone have one that runs, they want to part with it. I am ready to buy. With all the scammers, if you contact me, be ready to prove that you have it. My email is [email protected] I just want to drop in a motor and drive this thing as is. I'm not going to do much to this beast at all, just drive it all ratty looking. Not even going to fix the cracked window, in honor of the guy who sold it to me, and told me the story of how he cracked it.

Thanks yet again!

Those should be a "bolt in", although if taken from a "big" truck they may have extra "stuff" on the front of the engine like 3 sheave crankshaft pulley that would need to be swapped with your 228. There were also 236 and 256 cubic inch GMC engines built on this same design, but they are more rare than Jerry's chicken lips.

I've been involved with one rebuild of a 256, which was mostly used in WW II vintage Canadian military vehicles. It's an oddball combination of 248 and 270 components, and parts, particularly valves, were very difficult to find. 270s were used in thousands of WW II 6X6 trucks, and in the 1950's they were plentiful and cheap from surplus liquidators. Unfortunately, dirt track racers and Bonneville land speed record guys used most of them up. GMC engines respond to modifications MUCH better than Chevy. The survivors are scarce and expensive these days, and rebuild parts are getting almost impossible to find. I sent you a private message- - - -click on the flashing envelope icon at the top of the forum page. Good luck!
Jerry

JoeCole, The place to ask this question is by creating your own ad in the Truck Parts Wanted forum. Please be sure and read the forum "Header" at the top of the page and Swap Meet Guidelines before you post. Follow the info provided and get an ad up to help find the engine you want/need.

Don't forget to check out the Other Online Sources forum. Fellow Bolters post on line ads on such things as these engines they come across fairly regularly. You may find what you seek there too.

https://sfbay.craigslist.org/sby/pts/d/san-jose-1955-gmc-pickup-truck-3100/7758513254.html

Found this in under a minute on Craigslist. Search your area on CL and you will probably turn up something. If nothing in your localized area, you can utilize the map in the CL search bar. You might have to make a road trip to another state if you want one right now, as in yesterday. If you want a motor rebuilt, there are some very qualified individuals on here that will build or rebuild a motor for you. You just have to ask them and make a deal through private messages. Keep looking.

Twin Jimmys, Looks like JoeCole found an engine according to his post in Truck Parts Wanted. Maybe you want to post this find in the Swap Meet Other Online Sources forum so another fellow 'Bolter might take advantage?