88 turbo no boost with new bov, full boost on old
11-09-2012, 05:51 PM
#1
Instructor
Thread Starter
88 turbo no boost with new bov, full boost on old
Hi, Iv got a 1988 turbo 250 bhp stock. K26/8
My bov ( stock bosch type )was diagnosed as faulty at a car inpection. I removed it and tested the diaprham but pressing it up then covering the vacuum line nipple. The diaprham won't hold, just drops straight back down again.
However when running this bov I get full boost on the dash 1.8 bar around 3k rev in 5th and 3.2k in 4th
1st I replaced it with a baily dv30 alloy type. it wouldnt make full boost, 4k rev I would see 1.3 bar on the dash. This was 2nd hand unit, which worked when tested off the car. However I thought maybe once hot it would stick. I changed it over a few time and noticed that with the engine off, if I pulled the top vacuum line there was a release off built up air. Something I don't get with the old Bosch bov
So I thought I would just get a new Bosch type, well Bosch no longer make the 993 type bov 4 Porsche. I found a used Saab type, with brass ring. So I got that.
The Saab item is performing the same as the baily dv30. Not making boost and air is remaing in the vacuum line after shut down.
Anyone got any ideas on what's wrong? Why will my (torn diapham bov make full boost and the working ones not)
From the dash reading the bov is working b4 1 bar, clutch in the niddle drops instantly.
Iv replaced all the hard vacuum lines 4 new slicone ones. And just replace the set up as it was. Could I have this the wrong way? Dose the top vac line suck the diapham up on the bov when the trottle is closed?
My bov ( stock bosch type )was diagnosed as faulty at a car inpection. I removed it and tested the diaprham but pressing it up then covering the vacuum line nipple. The diaprham won't hold, just drops straight back down again.
However when running this bov I get full boost on the dash 1.8 bar around 3k rev in 5th and 3.2k in 4th
1st I replaced it with a baily dv30 alloy type. it wouldnt make full boost, 4k rev I would see 1.3 bar on the dash. This was 2nd hand unit, which worked when tested off the car. However I thought maybe once hot it would stick. I changed it over a few time and noticed that with the engine off, if I pulled the top vacuum line there was a release off built up air. Something I don't get with the old Bosch bov
So I thought I would just get a new Bosch type, well Bosch no longer make the 993 type bov 4 Porsche. I found a used Saab type, with brass ring. So I got that.
The Saab item is performing the same as the baily dv30. Not making boost and air is remaing in the vacuum line after shut down.
Anyone got any ideas on what's wrong? Why will my (torn diapham bov make full boost and the working ones not)
From the dash reading the bov is working b4 1 bar, clutch in the niddle drops instantly.
Iv replaced all the hard vacuum lines 4 new slicone ones. And just replace the set up as it was. Could I have this the wrong way? Dose the top vac line suck the diapham up on the bov when the trottle is closed?
11-09-2012, 06:14 PM
#2
Racer
Join Date: Oct 2008
Location: Tucson, Az
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Blowoff valve and cycling valve are 2 different things - the stock one does not vent to atmosphere, a "blowoff valve" does. I would think your car should have the stock cycling valve. Does all the plumbing hook up the same, or do you have an extra vacuum line?
Jeff
Jeff
11-12-2012, 05:45 PM
#6
Instructor
Thread Starter
Got both dump valves working. The oneway valve was piped in to the dump valve line, and shouldn't off been, strange that the car came that way, was working fine 4 the 6000miles Iv done and was probley like that 4 a while in the past owners ownership.
Interesting piped up this way, everything works on a fualty dump valve
Interesting piped up this way, everything works on a fualty dump valve
