Boost falling off

merkur

Registered User
I rebuilt my power steering pump a couple days ago, and I had taken the intercooler and upper IC hose off for more room to work. I decided to go ahead and pull the top off the blower to take a look at just how much of a restriction it really was. It was more of a restriction than I even thought possible, so I went ahead and ported it. I put everything back together useing silocone to seal the connections.( I had the hoses off before, and had no problem useing silocone) Now if I get on it, it boosts to about 9psi, and at around 3000 rpm the the boost starts dropping off rapidly to below 4 psi. Before it was makeing around 10 psi down low, and would creep up to 11psi by 4500 rpm. It would have to be a huge leak in my opinion to cause that kind of pressure loss. I tested for vacume leaks at all connections and found nothing. What did I do to my baby? Any idea's?
Danny
 
Sounds like one or both of the supercharger belts are slipping. Didn't by any chance spill some power steering fluid on them ?

David
 
Aw man! You are too smart! I didn't spill any, but the reason I rebuilt the pump was because of a leaking front seal. The leak got much worse right before I rebuilt it. I just can't get up to speed on the super charger thing. I have 17+ years working on turbo cars. Thanks a bunch. Do you think I will be able to clean them well enough to work, or will I have to replace them? They only a few hundred miles on them.
Danny
 
Aw man! You are too smart! I didn't spill any, but the reason I rebuilt the pump was because of a leaking front seal. The leak got much worse right before I rebuilt it. I just can't get up to speed on the super charger thing. I have 17+ years working on turbo cars. Thanks a bunch. Do you think I will be able to clean them well enough to work, or will I have to replace them? They only a few hundred miles on them.
Danny

Danny,

I would try spraying them off with brake cleaner while the motor is running.

David
 
Thanks man. I had allready bought the cleaner last night. I have a feeling it is going to take a few cleanings to get it all out. I'm just getting old I guess. I'll take care of it later today, and tell you if it works. Later
Danny
 
Cleaned the belts 4 times, and tried it out. It was much better, but still only making 9-10 psi until 4000 rpm and then it would fall off fast. I then noticed that the tensioner on the blower belt was extended all the way. I do have a 5% pulley on it, but it has been working fine for months. I am going to put a 5% jack shaft pulley on it soon so I didn't put on a shorter belt. Instead I removed the tensioner and drilled two new mounting holes about 3/8ths of an inch from the originals giving it a little more room to apply tension. It now pulls 9.5 psi down low, and goes to 11.5 psi by 3000rpm and holds it to red line. That may seem low to you guys, but at 7000 ft elevation it has to spin a bunch more to make boost. I am hoping for 14psi with another 5% overdrive. So thanks for the help. Later
Danny
 
mine does sorta the same thing whenever im driving normal and get around 2100 rpms it will go from around 5 psi to way down into the -8 vacc or what thats called...but when i nail it it seems to want to stay around 12 and doesnt lose any...BUT i am running rich for some reason and when the temps get up to about O R on norm... it seems to be really doggy and i cant get it to downshift if im goin goin above 30 and nail it. anyone know whats goin on
 
What is happening on your boost/vac guage sounds perfectly normal, as it is load based. Cruising along in any gear at 2100 rpm on a flat surface and no wind it should be be hovering around -12 to -18 in. The transmission sounds fine also. If you want to be in first gear at 30mph you will have to start out with the shifter in first, and hold it there until you are ready to punch it. I don't know what the exact calibration is on the automatics, but you would have to test until you find out the highest speed that it will kick down to first.
Danny
 
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