The Stovebolt Site Forums The Shop Area Engine Shop 1950 GMC 216 Cracked head - options?

Need some wisdom - 216 with cracked head, broken valve spring, and broken valve oiler tube.

Here is some background info on this sweet 1950 GMC 1/2 ton.
It was bought new from our local small town GM dealer.
Mrs. E. never licensed it and it never left the farm - probably never got out of first gear.
Was outside and lots of rust, but very low milage.
I am the 4th owner - bought it in 1999 - she was sitting on the side of the road, licensed and running - just couldn’t pass it by. 11,600 miles on the odometer - is this real? or has it gone around once. . . .
Locals say it never left the farm.

I did a major tune up the first year - new plugs points condenser, cleaned the carb, new fuel pump.
There was a very small leak of coolant from a small crack in the head on the left side below the rocker cover gasket near #5 cylinder.
Removed valve cover & adjusted the valves - lots of oil coming from all rockers at that time.
No evidence of any coolant inside - everything looked really clean - but that was 20 yr ago. . . .
Flushed the cooling system, filled with antifreeze to -40, and added some Gunk Block Sealer (Sodium Silicate), and cleaned out the crack and sealed with high temp epoxy.
Compression was great 110psi on all 6 cylinders

Since then I’ve done very little to it other than minor maintenance & change the oil and flush the brakes every year (did do a complete brake job - master to wheel cylinders)
Constant oil leak from the pan, rocker, & side cover - always need to add oil
“some day I’ll put new gaskets on them all”
Monitored the oil on the dip stick and at each oil change - never even a hint of water in the oil.
There has always been a few drops of coolant on that left head bolt, but never need to add coolant.
Blissfully ignorant.

April this year I brought her out of the winter shed (only run her 6 mo in the summer) did a minor tune up, and it ran GREAT.
18,000 miles - so I’m averaging 300 miles a year - just to the dump and back.
Compression #1-6: 130, 130, 98, 100, 100, 115 plugs all clean
It ran so quiet and smooth that I didn’t pull the rocker cover. - note to self - should do this every yr.
Idles real smooth & slow, and has good acceleration on the road. Hauled a few loads of manure, and it pulled well.

Early June, I did my first “big” trip - maybe 50 miles and it just ran quieter and sweeter - really likes 45 mph, so I take the back roads.
I noted that there was no oil leak from the engine now - maybe I just need to run it more. . . . (note to self - no oil leak could mean no oil....)
The dip stick still had clean oil and did not need a top up - hmm, usually it would need a quart after 2 months.

A week later (18,100mi) after sitting only 3 d it was hard to start and ran really rough.
Compression: 105, 108, 108, 111, 0, 118 gulp
spark plugs 1-4 were clean light white powder, #5 was black dry soot, #6 black & oily
Pulled the rocker cover - oh no - thick oily orange gunk caked all over the inside of the back half of the rocker cover and all over the rockers and valves - but only on the back 3 cylinders - front 3 look clean and oily.
The copper oil tube to the rocker is NOT connected - just hanging loose.
Broken valve spring with piece missing on #5 intake - valve is loose
Cracked spring on #5 exhaust but valve is tight.

I put a wood wedge under the #5 intake spring to pull the valve up - repeated compression = 118

Pulled the side panel - copper oiling tube had been rubbing on the pushrod of #4 intake valve and was broken clean off.
The back of the block under the side panel had some orange gunk dripping down the side, but the mid and front were clean and oiled. It would seem that oil changes and top up would keep some oil on the front 1/2, leaving the back 1/2 dry.

After a long day of reflection, I removed the broken spring and cleaned up around it. The gunk cleaned up amazingly easily and underlying metal looked pretty good (I thought). I can now see that the hairline crack extends across the rocker cover seal area, and up to the edge of the valve guide.

Photos attached.

As this is all new to me, I would sure like to hear this group’s experience and wisdom . . .

1 - Is the orange gunk typical of what you see with oil and coolant mixed. I’m guessing so, but would like some confirmation.

2 - Can a crack in this location be repaired? - I’ve read the tech tip on Lock-N-Stitch - is that an option here so close to the valve guide.

3 - If I’m looking for a used replacement head, does anyone know what years would be compatible (this is a 1950)
Would a 235 head fit from any years? Don’t know where to find this info.

4 - The gunk seems to be very localized, and it does not look like it has run into the drain openings.
I’m guessing the tiny amount of coolant leak inside the rocker cover would evaporate, and there was no oil flow to sweep it into the drain openings.
If some of this gunk got into the oil pan, how dangerous is it? (never saw anything in the oil change)
Will the block need to be stripped down as well?

5 - Grasping at straws - The Gunk Block sealer (sodium silicate) did seem to stop the leak for the first few years. The ads for Bars Leaks sound magical.
Has anyone had good experience with these products.

6 - If there is a very small continual leak of coolant into the oil, would you see this in the oil change? If you can't see it, does it still damage the engine.

Thanks for you help

Jim

The orange looks like rust. When oil and coolant are mixed it looks like thick coffee with a lot of creamer mixed in. That's why it's called milkshake.

That crack is long. Looks like a repair was attempted with JBW, or similar product. And the repair cracked and came off. Question then is where does the crack end and where do you stop welding? I would look for another head for a 216. There have to be a lot of them out there.

That head is very repairable. Since the crack isn't exposed to combustion heat and/or compression pressure, all the repair has to seal is cooling system pressure. That's probably 7 PSI or less. I'd suggest a good cleanup, wire brushing, bead blasting, etc. and follow up with a little air pressure and bubble soap to find both ends of the crack. Then stop-drill the ends to prevent any further spreading of the crack, and "sew" the area in between with overlapping tapered-thread cast iron plugs. The plugs and the tapered threading tap to install them are available on Ebay.
Jerry

Thanks, Jerry. My experience with crack repair is mainly in aircraft grade aluminum, which runs opposite to steel. The crack appears to have been aggravated by improper torquing of the bolt shown.

Thanks Fred - I'm on the hunt for another head - seems a good idea to have a backup.
Thanks Jerry - here is another photo after cleaning up and putting a couple lb pressure in the radiator. 90% of the leak is outside the valve cover, but there is that one drop inside. I can't clearly see the ends of the crack yet. Can you give some detail on how you do the soap bubble test - are you draining the coolant and putting air through the rad cap?

We usually did the air pressure test on a dedicated fixture in the machine shop, on a bare cylinder head. All the coolant ports were sealed off with clamping devices, and air pressure was applied to the head with a paint gun regulator. As long as you don't overpressure the radiator or the heater core, you could probably do the same thing by pressurizing the complete cooling system after draining the coolant. An atomizer bottle with a mixture of dish washing liquid and water, or a bottle of kids' bubble soap sprayed near the crack provides the leak detection. Another method would be to disconnect the radiator hoses and splice them together with flex hoses and a piece of exhaust tubing- - - -ditto for the heater hoses, and apply air pressure through a Schrader valve soldered into the radiator hose splicing fixture. You could also adapt an air line to the drain petcock hole and use a pressure regulator. That would take the radiator and the heater core out of the mix and allow more air pressure to be applied. Good luck!
Jerry

Thanks Jerry - lots of good ideas. I just built up a modified rad cap to apply 5 lb of air pressure there. I'll try draining the coolant and see if that is enough pressure to make bubbles. For the sewing, will I need to have the head off and use the drill press to get perfectly parallel holes, or is this a hand drill operation that can be done with the head in place? Any tricks on how to drill the curved surfaces?
Jim

I'd recommend a drill press, or a Bridgeport mill if one's available. For one thing, the shavings you'll generate with the drilling and tapping don't belong anywhere near an assembled engine. I usually spot-face a flat spot on a curved surface with a small 4-flute end mill and low speed in a drill press before center punching and drilling. You don't want the drill bit to wander and break. Once the patch job is done, you can put the curves back in with a die grinder and a carbide burr.
Jerry

Update - I cleaned the crack up really well and tried making bubbles with about 5 lb in the rad (heater bypassed). Got some nice bubbles outlining the crack outside the rocker cover, but nothing from the small crack extending into the "inside" of the rocker cover portion of the head.
I've been watching the videos from Lock-N-Stitch - it looks within my grasp, and also will be a big learning curve ( and that is the fun of why we do this. . . . )

then a used 1951 Chevy car 235 with attached car 3 speed transmission dropped in my lap that I can get for next to nothing.
The head looks good - pulled the rocker cover, and the rockers all look great (much better than my rusted ones).

I started a post in the drive train forum about using the car transmission.

My question here is --- if I rebuild the 1950 216 (actually, I just found a casting mark with a 2" circle and 48 in the centre - so maybe this is a 1948 vintage, and not the original engine ?). So if I rebuild the 216 or the 235 which will give me a better motor in the long run.

Thanks as always for the wise advice on this forum

Jim

A 1951 235 engine would have originally been installed in front of a Powerglide automatic transmission. There was no 235/3 speed option from the factory. That engine is just sort of an upsized 216- - - -it still has the Babbit connecting rods and spray-oiling system with the dippers on the connecting rods. One big difference is hydraulic valve lifters on the 235. The 235 will be virtually a drop-in swap, as long as the front motor mount at the timing cover is there. Powerglide cars had a different mounting system- - - -side mounts on the engine, and one at the back of the transmission. If the engine you have is already running a 3 speed manual, it's probably been converted to the bellhousing mounts and the single point mount up front already. Adjusting the hydraulic lifters so they don't rattle can be a challenge, but the original equipment lifters from the 1950's are MUCH better than the brand new replacements that are available today. Have fun!

The car transmission is a light-duty unit that won't bolt up to the truck driveline properly. The trucks got a beefier transmission with a different bellhousing bolt pattern in 1948, IIRC.
Jerry

Post the engine serial numbers here and we should be able to correctly ID what year your engines are. The stamped serial numbers are found on the flat machined surface next to the distributor.

Mike B

A 1948 216 that I'm working on currently also has that stamped number under the valve lifter cover, on the machined surface where the sheet metal cover bolts on, near the front of the engine. I was surprised to find it there during disassembly of the engine. It's in much larger letters/numbers that the one at the distributor location, and it's much easier to read. Has anyone else found similar markings on 216's? It certainly resembles a factory stamping, not something that's been added later.
Jerry

Thanks Jerry - good info - the 235 does have 2 front mounts at the front under the timing cover - fairly close together - and a hanger mount on each side of the bell housing.
The bell housing mounts do look different than the bell housing mounts on my truck - I'm guessing the position of the frame is different ?
If I'm reading this right, then the 235 should bolt fine into my existing truck bell housing - and I'll have to keep looking for a truck transmission.
I don't know what shape the 235 will be inside - so my plan would be to build an engine stand, and strip it down and clean it first, see if everything turns, before trying a start.
The water pump is seized - don't know what else is rusted inside.
But I don't have anything to loose, except time and having fun. . . .

Thanks Mike for offering to look at the serial numbers.
I believe these are both Canadian engines, and the numbers don't match to anything I see on line.
Did some more cleaning and looking, and came up with this:

My 216 has C377402 stamped on that flat surface right behind the distributor. It also has a cast mark between the breather and the distributor with GM followed by 48 inside a circle and underneath are 383-327 and underneath that is the single number 2
The head has a casting number under the rocker cover 3835517 and underneath that is also a single number 2
The VIN plate serial # is 093140836
my Maintenance Manual decodes this as 0 = 1950; 9=GMC; 3= 1/2 Ton; 1=116" wheelbase; 4= Pickup delivery; and the rest=vehicle number
the Engine code matches the code stamped on the engine: C377402
from chev235guy 216-235 Evolution the 48 inside the 2" circle between distributor and draft tube started in 1948 and was continued into 1949. The 1950 216 had a 2" circle by itself.
So it does look like my 1950 truck does have the original engine - and that is was a 1948 or 49 - interesting.

The 235 has the stamped numbers on the flat surface: 463608
And a casting on the extreme front ahead of the fuel pump: GM with an empty 2" circle, and underneath 3695408
I haven't been able to match those numbers to anything - it would be great if you have a reference.

Jim

That riveted-on plate must be unique to Canadian engines- - - -I don't think I've ever seen anything similar on a US-manufactured engine. Do the cylinder heads have the same number and arrangement of attaching bolts? If so, one option might be to swap the 235 head onto the 216, after doing whatever repairs or valve regrinding is necessary. Do both engines have a tall sheet metal side cover that goes up all the way to the valve cover? US-made spray oiler heads for 216's and 235's will interchange with no problems. Then you could work on repairing the cracked head and use it as you build up the 235 as a spare engine. There's somewhat of a learning curve involved in adjusting the rod bearing fit and oil clearance of a Babbit-rod engine. Good luck!
Jerry

Jim,

I personally won't be any help with your Canadian serial numbers, but we do have members that might be able to help.

Mike B

I am clueless; but, might this help a little?

This is what I got from the gmc site 0 is 1950, 9 is gmc, 3 is 9300 model , 1 indicates 116 wheelbase , 4 is cab type pickup delivery the rest of the numbers are the truck vehicle number .

Thanks Jerry and all,
I was hoping I might be able to just swap the head, but the 235 head has a different bolt pattern than my 216, and the 235 has the short metal side cover - so no go there.
Debating on getting the 235, building a motor stand, clean it up, and see if it will run, then swapping the whole engine - more work than I'll have time for this summer......

Back to stitching the head - I've contacted Lock-N-Stitch, and can get all the parts thru them to do the job.
They are recommending 1/4" dia. plugs.
It looks like the crack on the top follows the edge of the side wall of the water jacket - and is 1/4" from the edge (maybe 3/16" in one place)
If the drill holes are centred on the crack, that will leave 1/8" (maybe 1/16" in one place) of cast - that seem pretty thin.
Would you centre the drill hole 1/16" inside the crack to leave more of the wall in place?
I'm just rethinking if drilling the stitch holes will break out the side wall.
Knowing the crack is at least 20 yr old - could be rusted in the crack as well.

Any experience stitching that close to the sidewall?

Jim

Follow-up to Cracked 216 head - options
Please don't shoot me - after all the really good advice here, I decided to take the quick and dirty route as I wanted to use the truck before the summer ended.
So - drained the coolant level down below the crack - cleaned the crack area multiple times - solvent, brake clean, alcohol - then ground a shallow "vee" with a conical burr and Dremel tool - then JB Weld (the slow cure version) - let it cure 3 days.
Then topped up the coolant - and - the coolant seeped right through the thin portion of the JB Weld !
I thought that was impossible - photo attached.

So did a deeper "vee" and thicker layer of JBW and it held well.
I just unpacked her after winter storage, and so far the JBW is still holding well.

And - listening to others talk about a parts truck - I found a similar truck that had the cab removed but everything else there (though rusty). So I now have what looks like an intact head for rebuilding, and a transmission that looks good - and a whole bunch of other good parts.

More questions to come.
Thanks again everyone for your help.
Jim

If you need a better epoxy solution, consider Devcon Titanium Epoxy . It's made for this type repair. Can be machined and is considered a permanate repair. I used it to repair spindles in a small, lightly used backhoe. 5 years latter and still good.

RonR

Just for amusement I looked at Kijiji Kelowna...there's a guy in Summerland with 2 each 261 and 235 engines for sale. A rusty 1958-1962 Pontiac with a rebuilt 6 cyl is what I would be looking for. Good luck.

That plate is on the door pillar not the engine.

Jerry, that plate is the vehicle VIN plate on Canadian trucks. It is riveted to the front of the driver door jamb.

Edit: I guess I should refresh my browser occasionally. It seems Curt beat me to the punch! 🤦🏼‍♂️

Thanks Ron for the tip about the Devcon Titanium.
And thanks Curt for looking at Kijiji. I may end up going the 235 route eventually.
This 216 was rebuilt in Vernon at one time - no idea when.
It runs so smooth now - just hauled a load of manure yesterday.
Leaks oil everywhere
I'll start a new post on oil leak from the loose fuel pump rocker arm.

Follow up - The JB weld lasted through the summer, and then cracked right along the line of the crack in the casting.
Photo attached.
Now looking at refurbishing a head from a 1947 Chev Sedan....
New link here: https://www.stovebolt.com/ubbthreads/ubbthreads.php/topics/1474082/drilling-out-valve-guides.html

That's actually pretty neat that you bought a little time with that. Can it be properly brazed?

All 216, and 235 from 1941-52 (including the "Powerglide" engine) have the same 15 bolt pattern. Only the 1953-63 235 (and 261) have the later 18 bolt pattern.
The 216 and early 235 valves are the same size (except Powerglide). The stem OD is .341".
There may be other compatibility differences.