AIR system ?'s

[Ttype83]

If the check valve on the AIR system fails allowing exhuast back on the pipe to the diverter valve, what will it do to the system??
Will the AIR by pass valve just dump it or will it back up in to the vac system causing other problems(like low vac and/or over boosting)?
I see how to check the check valve, but nothing says what a bad one will do to the system.
I ask because I was checking for vac leaks and I removed the pipes going to the check valve and saw some black soot in the pipe. I did think much of it until today after picking up my car at a buick dealer, I had them try to find the leak/problem.
I have low vac at light take offs and under light loads(going up hills on the HWay)
At a stop under heavy acceleration boost only goes to about 7-10
(I have it adjusted low)
But when I'm cruising and step on it, boost will climb above 12 before I have to get out of it to stop from over boosting.
I know that I have a problem with my TC some were too, it engages(got it sp) & disengages at will and I can not manually keep it locked.

 

[b4black]

I believe that the vacuum lines, the boost lines and the AIR lines are all seperate from each other.


I see the exact same boost levels as you. The actuator should hold max boost better than that. I would first check an make sure your actuator isn't blown. Also check all of the boost lines for leaks. That includes the MAP sensor and boost switch lines.

If thier OK, you might have boost creep. Even though the WG is opening, it's not passing enough exhaust gases. Either the puck isn't opening fully or the hole is too small. A inline relief valve before the actutor might help. The relief valve set at max boost and the actuator set at max boost minus ~4psi. Then when the relief opens, it pops the WG puck open fully. Otgherwise, you may have to remove the turbo and open the WG hole just a little.

 

[Ttype83]

Originally posted by b4black
I see the exact same boost levels as you.

Do you have low vac at take offs & light loads?

The actuator should hold max boost better than that. I would first check an make sure your actuator isn't blown. Also check all of the boost lines for leaks. That includes the MAP sensor and boost switch lines.

That was the first thing I checked, just replaced it last fall.
I have either replaced or checked my lines withoout rfinding a leak. I had low vac before and it ended up being my boost switch, the nipple was rusty and would not hold the hose on. I fixed it with a brass peice & expoy. I'll take a pic when I get a chance.

If thier OK, you might have boost creep. Even though the WG is opening, it's not passing enough exhaust gases. Either the puck isn't opening fully or the hole is too small.

Ok, I wonder if the puck is cluged....I'll have to clean out one side of the garage to get my car in(cold & raining here) & try and check it. Can I clean the puck hole with carb cleaner?

A inline relief valve before the actutor might help. The relief valve set at max boost and the actuator set at max boost minus ~4psi. Then when the relief opens, it pops the WG puck open fully. Otgherwise, you may have to remove the turbo and open the WG hole just a little.

I had thoought of this but was unnwilling to until I tried to figure out what was wrong.
I droped my car off at the buick dealer yesterday for them to run a diag on the car to help find the problem. I had asked sevreal times if they had some one that new this cars. His asnwered each time that they sure did. They called me with in 2 hours asking why I had replace the plug wires I should have gone and picked up my car right then.
I picked it today, they said that the only thing that they could think of was the carb not giving enough fuel. Well no fix no charge....
Thanks Rich
Jim

 

[Ttype83]

Doug Roe actually talks about this at the end of his book.
If the check valve fails allowing exhuast gas back up, it'll back up into the compressor. This will damage the compressor. I found this when I was opening up the spare carb to tweak it & going back over the book.

I rechecked my actuator off the car with a vac gauge, it's leaking from the pressure side to the vac side I just got this one late last year) I blocked off the vac side to stop the leak & I'm calling the company I got it from.
This still did not solve all the low vac, but it did help some.