Hello everyone, I recently got my 228 together and running after having the water pump and head rebuilt. As I was burping the cooling system I noticed that I wasn't getting any flow from the head to the radiator. I checked the thermostat it was good. I even removed it and ran the engine, but I still wasn't getting any flow or pressure built up in the system. Well, I ended up burning up the head gasket in the process, so I'm back to square one. I'm new to these old engines so help me out here. One thing that I can't wrap my head around is, if guys are running a 4psi radiator cap, how is that metered without being able to bleed off the excess pressure? On my radiator, there isn't a bleed line on the fill neck like there is on newer cars. I really don't have the time and money to go through this again, so I'd like to figure this out before replacing the gasket again.
Tim, I just ordered one. I know that the Chevy and GMC engines are different. I was just assuming the cooling system was basically a standard system. I must be missing something though. A stupid mistake on my part. I tend to make assumptions and rush things and this is usually where I end up. I could write a book on learning the hard way.
One thing I did notice is during startup I had some metal to metal squealing going on. It went away after a few minutes. When I pulled the pump and backing plate off I noticed that shaft and the impeller were rubbing against it. I choose not to used a gasket there, only RTV. So maybe the gasket thickness would have prevented it. It doesn't look like it was enough friction to stop rotation. The belt would have been burning anyways. Just something I noticed.
I also forgot to add that when I got the truck from my grandpa, it had a blown head gasket already.
I checked the radiator and it flows top to bottom just fine. I also pressure tested it and it passed. There is a bleed line on top that is constant. With pressure constantly applied, it would bleed enough to maintain 4psi+ no problem. I also check flow through the block and head and it was good.
Just spitballing here. When you replaced the head gasket did you double check to see if all the passageway holes lined up?
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back to thermostat - can you remove it and test it? Put in a pan of hot water and bring to boil and watch it open? Other than that - I'm assuming air is out of the system, block was flushed and radiator cleaned out. I recently cleaned a tractor engine by removing the freeze plugs, pouring a mix of water and vinegar, and using a compressed air - repeated that about 6 times until all the crud was out. Removing and putting new freeze plugs back in is a snap.
Check that "rebuilt" water pump to be sure the impeller is turning. Can you flow water through the engine and out of the thermostat housing by attaching a garden hose to the pump inlet? Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
And on top of everything, the newly rebuilt water pump is already leaking out of the weep holes. And there is rotational play in the shaft. Unbelievable.
Reinstall the pump and try spinning it backwards with a drill motor to see if it pumps that way. It sounds like your so-called rebuilder needs to try again. Is there a warranty? Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
It's been almost two years since they rebuilt it. I emailed asking them to take it back, but I'm not holding my breath. I hate to threaten them with a negative review, but it was a [censored] poor rebuild.
Is it possible that the cooling system was not completely filled starving the water pump?
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That is what happened initially. I realized it and continually added coolant and still had the issue. Could there have been a large enough air pocked in the head to cause this?
Yes, it's possible. I usually do an initial fill through the open thermostat housing, then when the coolant level stabilizes there, install the thermostat and upper radiator hose and continue to fill. Drilling an air vent hole about 1/8" in diameter in the thermostat is also a good idea, and cheap insurance. The water pump impeller MUST be submerged to move any coolant- - - -it's not a self-priming pump. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
GMC water pumps are an old ball. Seem to be in short supply and expensive. Mine was junk. Sent it off to be rebuilt. I did not remove the back cover when it returned. It looks like the first picture.
You do not mention your chassis size ? 100 to 350 series GMC in 1947-1950 shop manual says the stock cooling system was a non pressure ( atmospheric) system. There a note : All except the 100 series can be changed to pressure system. A larger core is used on the pressure system. If it is pressure system it has a 4 psi cap And has a built in recovery tank.
My 100 is a non pressure system. It’s impossible to see coolant flow in the stock radiator. The top hose is several inches from the filler neck. I run a 180* tstat.
Shop manual is very confusing on the water pump. See the attached pictures. From the pictures there appears to be two different pumps. There is no mention of two different pumps in the text. The pictures show the impeller in two different orientations.
Your picture looks suspect as far as the impeller orientation. The leaking at the weep hole is an obvious concern.
On the blown head gasket. Was the head and or block surfaced on the last repair ? Since the original head gasket was blown...........the head or block might not be flat in the blown area.
The block: The lower back water passages in the block are well known to blocked with rust and debris
You all are great! Thank you all for the help! Very much appreciated.
It's a 53 1/2 ton. 228 block with a 270 head. It makes sense that the system is non pressure. I should have learned that ahead of time. I did notice on my pump that there is a larger gap between the impeller and pump body. Probably not enough to significantly affect flow.
The head was resurfaced when it was rebuilt, but not the block. It wasn't in the budget then, but now I might just save up and do it too. It would be a good opportunity to hot tank the block and clear out the coolant passages.
Showkey, where did you send your pump off to be rebuilt?
I can’t put my finger on the paper work. I think it was a guy on eBay in Georgia. I did not buy using eBay, I dealt with him direct. This was a few years back and the choices were very limited. I recall at the time, you could buy a parts rebuild kit ......but......was the same price as the rebuild.
Took the head off today. All the coolant ports were clear. I ran air through all of them. Take a look at the photos. Besides one port that looks like a definite culprit, I can't tell where coolant was making its way into the cylinders. One thing I forgot to mention that I thought was weird, was when the engine was running after I saw coolant coming out of the exhaust manifold, the compression of the engine never blew back into the cooling system. Shouldn't that have happened?
Like most people do, you got impatient and took the thing apart before you found the source of the problem. Now it's going to be a guessing game to figure out what, if anything went wrong. Good luck! Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
You're absolutely right Jerry. I did find out my grandpa had engine work done back in the early 90's on it. New pistons. and head work. He said the bottom end wasn't removed from the truck, so we don't think the block deck was milled. But, it's reassuring that after the work he drove it for many years without issue. I'm trying to get in contact with the mechanic that worked on it, because on the receipt, it say the crank was welded. What would he be referring to?
Crankshafts with badly worn journals or spun bearings can have material welded onto the journals and reground back to the proper diameter. That requires a total engine teardown, so if that has been done the whole engine has been disassembled and rebuilt. I would have tried to find the head gasket leak by either putting air pressure into the cylinders one at a time to figure out where to start looking for a problem, or bypassing the radiator with a couple of hoses and attaching a garden hose to the cooling system. With the spark plugs removed and a few pounds of pressure applied, water will squirt out of one of the plug holes, showing the general location of the leak. If you're getting water out of the exhaust, it's possible there's a crack in the head that goes into an exhaust passage. That can also be found by pressurizing the engine, but the intake and exhaust manifolds have to be removed. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
After looking more closely at the deck of the block and considering the condition of the engine when I received it, I've come to the final conclusion to pull the block have it serviced.
Here's kind of a timeline that has lead to this conclusion. 1981- the engine was rebuilt. Grandpa drove it up until about 2000. At that time I helped him replaced the exhaust manifold gasket. 2000-2017 It did not run or move. When I got it running in 2017, the engine compression was blowing into the cooling system. I pull the head off and had it rebuilt. During this time, I noticed that exhaust manifold was very, very rusted. All of the mating surfaces were so pitted they were not functional. The Intake mounting studs were rusted almost all the way through and could not be removed. The intake warming flapper was also seized in place. I didn't think much of this until now. Keep in mind. The truck has spent it's whole life up here in Northern CA. We don't get a ton of rain and humidity is always very low. I was able to find a replacement out of New Jersey that was in much better condition. So I installed the head and ran the truck again and I now have coolant leaking into the cylinders and out into the exhaust manifold again. When I looked closely at the condition of the block deck, I have found some very deep scratches that lead from and to coolant ports and cylinders. I know for a fact that I did not create these when I removed or installed the head. They are deep enough that head gasket would not be capable of sealing, especially being the metal side of it and not the fiber side. I believe these were created when the engine was rebuilt in 81. Maybe it didn't leak coolant much at first, or it had gone unnoticed by my grandpa. But the condition of the exhaust manifold leads me to believe that this has been an ongoing issue. Take a look at the photos. There is also some serious damage to two cylinder walls. I guess a complete overhaul was inevitable.
A good heavy coating of COPPER COAT would take care of those scratches, can't really see how much coolant could get through them. I would take a new file and run it across those numbers stamped in the block, they look a little high.
