gillis valve gone bad?????

Does anyone know if a gillis valve can go bad? I've had mine on my car for about 1 year. I had it adjusted to 20psi for normal driving and it was working fine. The other day I was at a light and floored it since a mustang was in the other lane, and I flew up to 25psi and my boost buzzer went off. It is now limitless and I would like to know if that is the problem or if it could be somethin else.

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1988 Turbo Coupe, 5-speed, loaded, silver, two-tone raven interior, five star rims, Sequential turn signals, T3 turbo, ported out E6 manifold, Gillis Boost Valve, Custom Cold Air Intake, Ported head, Ranger roller cam, 2.5" full exhaust (no cat) dual dynomax ultraflows
1974 Lincoln Mark IV- Black/Black leather 95% restored, 460ci, 4bbl.
1977 Ford F150- 300ci. straight 6 (needs a new bed)
2002 Chrysler Sebring LXi Convertible- Maroon/taupe interior
1980 Bronco 4x4- 351ci. 4bbl

They can fail like anything else can. It's very simple to take apart and look at the spring and the seat, check for debris. What I don't like about the valve is that it's nothing more then a spring actuated pressure relief valve and it doesn't provide smooth modulating pressure for the wastegate. It is a very reliable valve.

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85.5 TC 5 speed, Ranger Roller cam, 3" exhaust system, manual boost valve, large VAM, SVO PE computer, front mount Motorsport intercooler & sport grille, ported upper and lower intakes,flow matched injectors, ported E6 manifold, 245/45/17 wheels & Tires,140 mph speedo,Motorsport lowering springs, under restoration

Also make sure the small bleeder hole (opposite the outlet/wastegate port) is open.

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88 Silver T/C, original owner, 252,000 miles
Loaded except leather & auto trans
K&N, Gillis, SVO roller #1, big SS valves, ported intake, head, & exhaust
Polyurethane bushings throughout, Goodyear GT-HR 235/55R16's

I would check out the wastegate also. If you can adjust the Gillis valve and it still boosts unctrollably then it would be wastegate related.

Actually the overboost buzzer should go off around 18psi. Are you basing that 20psi on the factory gauge?

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mods: SDS Digital Fuel Injection, ported & polished big valve head(1.89/1.59), Esslinger roller cam #2277, Esslinger adj. cam pulley, custom upper and ported lower intakes, 60-1 stage III .63 turbo, powerstroke intercooler, 60mm throttle body, 75pph injectors, Walboro 255HP pump, Kirban adj. fuel reg., ATR header, 3" exhaust with Dynomax Ultraflow muffler, MSD 6al, MSD coil, MSD Launch Control, MSD 8.5mm wires, K&N filter, Spec stage III clutch, Greddy Profec B boost controller, Weld Draglites with M/T ET Street 26x11.5/15

I have an aftermarket autometer gauge hooked up and in place of the factory clock. It shows +/- vaccuum. It is pretty accurate. I'll have to check the wastegate arm. Last time the little c-clip fell off and it was stuck shut...maybe it is now just stuck open?

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1988 Turbo Coupe, 5-speed, loaded, silver, two-tone raven interior, five star rims, Sequential turn signals, T3 turbo, ported out E6 manifold, Gillis Boost Valve, Custom Cold Air Intake, Ported head, Ranger roller cam, 2.5" full exhaust (no cat) dual dynomax ultraflows
1974 Lincoln Mark IV- Black/Black leather 95% restored, 460ci, 4bbl.
1977 Ford F150- 300ci. straight 6 (needs a new bed)
2002 Chrysler Sebring LXi Convertible- Maroon/taupe interior
1980 Bronco 4x4- 351ci. 4bbl

might also check for a leak between the valve and the wga (hole or crack in hose, etc). I've had no problems with my gillis so far. Oh course I just got it back to boosting above 9psi. Some kid rebuilt the turbo last time, all I can say is WOW! striped bolts, some not even there, and he left one of the oil return line bolts loose. Now all i need to figure out is my shuddering under boost problem.

Originally posted by servingGod:
Now all i need to figure out is my shuddering under boost problem.

Is it a shudder you feel through the gas pedal? When is last time you changed the cap, wires and rotor. Wires can cause a shudded type miss like this.



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mods: SDS Digital Fuel Injection, ported & polished big valve head(1.89/1.59), Esslinger roller cam #2277, Esslinger adj. cam pulley, custom upper and ported lower intakes, 60-1 stage III .63 turbo, powerstroke intercooler, 60mm throttle body, 75pph injectors, Walboro 255HP pump, Kirban adj. fuel reg., ATR header, 3" exhaust with Dynomax Ultraflow muffler, MSD 6al, MSD coil, MSD Launch Control, MSD 8.5mm wires, K&N filter, Spec stage III clutch, Greddy Profec B boost controller, Weld Draglites with M/T ET Street 26x11.5/15