Coolant Bypass Nipple on 948 Welded Closed - Advice needed

[Jim_Gruber]

So I have discovered the Coolant Bypass hose fitting on the bottom of the head on Bugsy IV's 948 has been welded closed. WTH. What is that going to do to this engine or does it make any difference. It appears from MOSS Catalog that is a screwed in fitting but trying to remove from a 56 y.o. engine a fitting that is undoubtedly RIP ( That's Rusted In Place ) while head is installed could be challenging. So do I need to worry about it. Or just block the fitting on the Water Pump with a piece of heater hose and a pipe plug of the correct size. Advice needed. TIA Guys

Radiator out getting cleaned and tested, thanks Bill M. for shipping me your old spare several years ago as it is the best of the 3 948 Radiators in my garage right now. The one that came with Bugsy IV had the Temp Gauge fitting twisted off. Hence the need to replace my dual gauge as well. Parts order from AH Spares with Replacement hoses and lot's of little parts and pieces should be here by late in the week. A full scale Thrashing is planned for next weekend. Compression Test is set for tomorrow. In the meantime need to get Bugsy IV on jackstands and see if there are any brakes installed. E-Brake doesn't work and need to discover if it is even connected, or if there are brake shoes to pull against. Discovered sticking throttle cable, glad to know before I try to start, also will take linkage apart at the pedal and validate the I don't have issues there. It's coming together. Hope to be driving by British Car Days Show on August 6 in Dayton.

 

[hcallaway]

I want more pictures!

 

[BlueMax]

I don't run them!!

 

[Billm]

Be sure to drill a small (bypass) hole (around 1/8") in the perimeter of the thermostat and leave everything else as it is
BillM
-glad that the radiator will work for you!-

 

[Jim_Gruber]

So simply plug the water pump nipple and make sure bypass hole is in the Thermostat - Got It.


Regarding Pictures. Impossible to take without taking the head off. Perhaps a mirror. Hmm

 

[dklawson]

If originality is important to you, you can drill out the old fitting in the head and replace it with new (part number 12A2075) . Obviously that's a "head off" job. However, the thread is odd (5/8-16?) so many people with A-series engines don't bother. As above, they drill a few 1/8" holes in the T-stat and cap the hose nipple on the pump.

Jim, the dual gauge can be repaired. Professional repairs often cost as much as a new gauge. However, you can repair it yourself if you are careful. See the link below for the procedure. I have used this method on about 1/2 dozen gauges. The only thing I do differently is that I use dry ice for the cooling bath.
https://www.ply33.com/Repair/tempgauge

 

[nomad]

If originality is important to you, you can drill out the old fitting in the head and replace it with new (part number 12A2075) . Obviously that's a "head off" job. However, the thread is odd (5/8-16?) so many people with A-series engines don't bother. As above, they drill a few 1/8" holes in the T-stat and cap the hose nipple on the pump.

Jim, the dual gauge can be repaired. Professional repairs often cost as much as a new gauge. However, you can repair it yourself if you are careful. See the link below for the procedure. I have used this method on about 1/2 dozen gauges. The only thing I do differently is that I use dry ice for the cooling bath.
https://www.ply33.com/Repair/tempgauge

Jim, the only thing that bypass hose is for is to couple with a British thermostat that hasn't bee available for many years. The original thermostat would blank off the bypass hole when the engine warmed up The purpose of the bypass was to allow quicker engine warm up.
With the thermostats we have today all it accomplishes is to make the engine run hotter. The bypass is on both the A and B series engines and I always block them off one way or another. On the B series its internal to the head and block so a blanking sleeve is necessary. On the A series the tube in the head is usually impossible so I put a short piece of appropriate sized rod inside the hose. Drilling a small hole in the thermostat flange is necessary to let the air out when you are filling the system. The thermostat doesn't want to open when its inside a pocket of air and your head doesn't cool very well that way either. I usually just drill a 1/16" 3/32" hole for the air if the thermostat doesn't have a bleed valve already. Old ones used to but I believe that manufacturers no longer bother.

Kurt.

 

[Jim_Gruber]

Thanks Kurt, the light bulb comes on as to it's original purpose for that hose. I.ll make sure to add the holes to the new thermostat.thanks.