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MGB Seized air pump issue

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Celtic 77

Celtic 77

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On the way to get our Jetta in for a new timing belt, I drove our B as our replacement car. Started hearing a screeching noise, and the sound of a snapping alternator belt. Obviously, we left the overheated B at this repair shop. They called this AM stating that " Found vacuum pump pulley to be seized causing belt to shred off alternator. Vehicle needs vacuum pump assembly. Next sentence, " Alternator belt shredded due to alternator pulley not being properly aligned with other pulleys in system." Installed spacers and new belt." "Advise several bolts were loose and backed out." Total? $230.00. They charged me $40.00 for the alternator belt...seriously. I told him I replaced mine for $6.00! Several discrepancies... seized air pump pulley caused Alternator belt to shred off alternator. Then next sentence says it was the alternator belt that shredded. Scammed? I don't know. The air pump belt was fine when I checked....
 
...if it smells like a fish...

"Spacers"? Like a pile of washers or the like?
 
I never had a "B" with an intact air pump, so I'm not 100% sure on this but if belt that drives the pump also turns the alt (or is a secondary belt driven by the alt) it could easily have caused either or both belts to shred - important question is this: Is the air pump actually seized?

Their description is anything but clear, and they seem to be claiming there are 2 different issues. Either way, $40.00 for a V belt seems high and I'd really want to see the pully alignment mismatch before having them "fix" it...
 
YakkoWarner said:
I never had a "B" with an intact air pump, so I'm not 100% sure on this but if belt that drives the pump also turns the alt (or is a secondary belt driven by the alt) it could easily have caused either or both belts to shred - important question is this: Is the air pump actually seized?

Their description is anything but clear, and they seem to be claiming there are 2 different issues. Either way, $40.00 for a V belt seems high and I'd really want to see the pully alignment mismatch before having them "fix" it...
Click to expand...
I picked up the B and we had a little "reeducation" class. They realized that the air pump was an entirely different system. I told him to take the air pump belt off and just do the overly expensive alternator belt. Mechanic said the alignment of the water pump and alternator pully was off about 1/4". Spoke to Moss tech and said it was ok to remove smog stuff without major headaches.
 
Would be checking the water pump and alternator for soundness and proper fitment if this was a ā€œnewā€ issue.
 
My 72 MGB air pump. PJ

72ENG1.jpg
 
Does the air pump system push air into the intake or exhaust chambers inside the head? I always assumed it was pushing air into the exhaust stream, but I never had the nerve to unplug one of the ports to see what came out....knowing my luck I'd strip the threads and never get it back in.
 
My new project will be to "detox" the car. Old MG book gives a pretty simple explanation. The pump pully is seized. And NJ has no emission inspection for classics.
 
Grantura_MKI said:
You can place Allen drives in the hole on the head and fill them in.
Click to expand...
Translation: Allen head set screws. šŸ˜‰

Pump makes a diluted amount of pollutants come from the tailpipe by introducing forced ambient air into the exhaust ports. It's a vane pump. The blades rust and corrode, then become stuck in their "slides" and seize the pump.
 
Last edited:
DrEntropy said:
Translation: Allen head set screws. šŸ˜‰

Pump makes a diluted amount of pollutants come from the tailpipe by introducing forced ambient air into the exhaust ports. It's a vane pump. The blades rust and corrode, then become stuck in their "slides" and seize the pump.
Click to expand...

Mine just has bolts threaded into the ports on the head - the allen head set screw method would be a neater/cleaner looking method.
 
YakkoWarner said:
Mine just has bolts threaded into the ports on the head - the allen head set screw method would be a neater/cleaner looking method.
Click to expand...
Don't recall the thread pitch or size, shouldn't be a problem to measure it tho. I've even seen some original ferrules with the tubes bent over, crimped and welded shut. "Crude but effective."
 
About ready to jam a wooden dowel into the air injection ports! The 7/16-20 that John Twist and others say to use are too small for my application. Off to Lowes/Home Depot with hopes and crossed fingers.
 
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