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I just replaced all rubber hoses with new repros, and installed a correctly dated and rebuilt water pump. There is a minor leak that I can't stop coming from the end of the lower radiator hose connection to the water pump. A repro hose clamp (shown in pic) was crap and I replaced it with a very heavy duty clamp from NAPA. Still leaks, even when I added a second screw type hose clamp! I had the same problem with the upper hose to the thermostat repro clamp, and replaced it with original Witeck clamps that I had. That solved that.
The new radiator hose fit very tight onto the water pump outlet. But do these old water pumps tend to have a rough surface and too many pits (painted over) to form a tight seal against the inner hose surface? In the past, I would use gasket cement to help seal the hose connections. I didn't this time though. The temp gauge also shows it running slightly hotter than I normally run (@200* instead of @180*). Could it be a bad rebuild causing the pump to not flow adequately, thereby raising my engine temp and causing back pressure to leak out of the hose?
1966 427/390 water pump hose leak, past hose clamp
Check that weep hole but I've not been beyond slathering some Permatex around those pitted water pump/thermostat connections to help seal the hose to the nipple...
At the risk of asking the obvious - It's hard to tell from the picture, but are you sure that the hose is long enough and thus is fully seated (all the way up) on the pump outlet, and that the clamp is then seated above the "nub" on the outlet?
I have seen cases where the clamp was installed on top of the nub, making it impossible to get a good seal.
I agree that some sealant - use a silicone base, it's easier to remove later - is a good idea in any case.
I'll check the weep hole. But in that case, it would be a bad rebuild, wouldn't it?
The hose is seated up as far as it will go. And the clamp is screwed down just past the nipple. I also added a second hose clamp to the hose, right on top of the nipple area, I'm amazed that anything can get by there. I guess the next step is to coat the water pump outlet with gasket cement and hope for the best.
I would use dielectric grease or just some chassis grease, and coat the lining of the hose where it would interface on the pump. That would stop a leak long enough to isolate it to that area before you slather it with silicone.
Twist a piece of paper towel or toilet paper into a point and shove it in the weep hole and see if it gets wet.
No chassis grease on the water pump outlets, please! (Petroleum rots rubber). What as worked for me very well over the years with rough castings or corroded radiator/water pump outlets is old fashioned Permatex. It'll fill in the voids and set up. Worked great on the 1912 radiator I'm running in my Model T.....
Do what the factory did........put in a little Stop Leak for aluminum radiators. I had a problem with a very small leak on the bypass elbow on my water pump. I added about 1/4 of a can, and it stopped the leak. That was 8 years ago, and still no leak. Worth a try.
I just replaced all rubber hoses with new repros, and installed a correctly dated and rebuilt water pump. There is a minor leak that I can't stop coming from the end of the lower radiator hose connection to the water pump. A repro hose clamp (shown in pic) was crap and I replaced it with a very heavy duty clamp from NAPA. Still leaks, even when I added a second screw type hose clamp! I had the same problem with the upper hose to the thermostat repro clamp, and replaced it with original Witeck clamps that I had. That solved that.
The new radiator hose fit very tight onto the water pump outlet. But do these old water pumps tend to have a rough surface and too many pits (painted over) to form a tight seal against the inner hose surface? In the past, I would use gasket cement to help seal the hose connections. I didn't this time though. The temp gauge also shows it running slightly hotter than I normally run (@200* instead of @180*). Could it be a bad rebuild causing the pump to not flow adequately, thereby raising my engine temp and causing back pressure to leak out of the hose?
1966 427/390 water pump hose leak, past hose clamp
you have an air bubble in the system check overflow tank if low add to half full.Run it and get the air out temp
will go down.
[QUOTE=Roger Walling;1590294095]Sometimes the casting has a flash line that was not ground down enough and does not allow the hose to seat.[/QUOTE
Well..... it was just the opposite. Take a look at the flat spot that's ground into the outlet on the bottom side, exactly where the hose leak was coming from. I sanded it down and used lacquer thinner to reveal this (using a mirror).
NOW, what do I do (besides find that p.o.s. that sold me this defective rebuilt junk core on *bay)?! When I first received it, the heater hose outlet tube was flat on one edge, as if it had been dropped. I contacted the seller then, who played dumb, and I tapped it round with a ballpeen hammer. But THIS really p*sses me off! It's dated properly and cost me some bucks.
If I remove it, I'm just going to replace it with either the old (non GM) pump that I removed, which still worked fine or buy a new one over the counter (non correct date and probably non GM, of course). Buyer beware is right. That's why I usually stick to only Corvette vendors (except one on here who regularly posts specials, who also screwed up an order big time, and I'll never deal with again).
I am grateful for all of your responses on this, and I never pretend to have all of the answers. That's why I love this site. So if anyone has encountered this type of problem and knows a way around it (besides a hot glue gun, LOL) please feel free to suggest something. Otherwise I'm replacing this sucker and making the next show this weekend!
Flat spot on 1966 date coded 427 water pump (bottom of outlet tube viewed with mirror).
Last edited by big block ken; 08-18-2015 at 08:03 PM.
I guess you still could have an air bubble in the system Thanks
I really appreciate the input. Sorry I was rather short in my response (I had just discovered the cause of the leak). And I wish it was an air bubble. Check out my picture of what's causing this leak. UGH. It's amazing what some Chevy orange paint can cover up.
I really appreciate the input. Sorry I was rather short in my response (I had just discovered the cause of the leak). And I wish it was an air bubble. Check out my picture of what's causing this leak. UGH. It's amazing what some Chevy orange paint can cover up.
Put some JB weld on it smooth it in all the pits sand it down and that
should fix it just my 2 cents .
The number matching pump I got had the plate bent up I had to take apart and fix mine it was leaking . I also got it on E-Bay.
Your right when there's a leak it will raise the temp ,once you fix the
leak it will be good to go I would fix it .Because of numbers matching.
That's a good idea. I've used J.B. Weld before, but never on cast iron auto parts. I would think it would hold up to heat and anti-freeze, so I'll give that a try tomorrow. I wonder if we bought our "rebuilt" pumps from the same guy. It's a family business in Oregon and I just wrote him through *bay.
That's a good idea. I've used J.B. Weld before, but never on cast iron auto parts. I would think it would hold up to heat and anti-freeze, so I'll give that a try tomorrow. I wonder if we bought our "rebuilt" pumps from the same guy. It's a family business in Oregon and I just wrote him through *bay.
The guys I got it from is called enginehunter he said he's getting old and didn't catch the bent piece .
These pumps are getting harder to find and more expensive
I fixed mine couldn't find another one .Mine had the rough surface
also I got lucky at 110 dollars
08-17-2015, 12:04 AM
Leaking lower hose at water pump issue
I guess the next step is to coat the water pump outlet with gasket cement and hope for the best.
When I first received it, the heater hose outlet tube was flat on one edge, as if it had been dropped. I contacted the seller then, who played dumb, and I tapped it round with a ballpeen hammer. But THIS really p*sses me off! It's dated properly and cost me some bucks. 
That's a good idea. I've used J.B. Weld before, but never on cast iron auto parts. I would think it would hold up to heat and anti-freeze, so I'll give that a try tomorrow. I wonder if we bought our "rebuilt" pumps from the same guy. It's a family business in Oregon and I just wrote him through *bay.