lostinthe202 Posted March 18, 2009 Report Share Posted March 18, 2009 1985 720 z24 4x4 This was broken when I bought the truck, hoping it's responsible for my high idle. Can anyone tell me what it's called and what it does? It's on the intake manifold and coolant comes pouring out if you take it off, go ahead ask me how I know... Thanks! It's the black thing on the left with the broken hose barb. Quote Link to comment
nis720 Posted March 18, 2009 Report Share Posted March 18, 2009 Some sort of vacuum silenoid that works of water temp. I might have mine laying around somewhere in my garage. Quote Link to comment
datzenmike Posted March 18, 2009 Report Share Posted March 18, 2009 Yes, that's the TVV Thermal Vacuum Valve. The valve when warmed by coolant closes an air bleed. Now it allows full vacuum to the charcoal canister purge, Allows RGR (only on a warm engine) and allows full vacuum advance on the distributor (only on a warm engine) The bottom hose is for distributor vacuum advance, the middle hose is for canister purge and EGR and the top hose is the bleed that draws filtered air from the air filter housing. If it is broken, the TVV will work perfectly normal, the only difference being that it draws unfiltered air when the engine is cold. This is not something that needs replacing right away. Quote Link to comment
lostinthe202 Posted March 18, 2009 Author Report Share Posted March 18, 2009 Hmm... so not my high idle problem, damn. I picked up vacuum hose, but I haven't had a chance to replace. Everything on the carb is in good shape so I'm still looking for other causes. When I saw this I got all exited. So not something that needs replaced right away, hopefully the dealer still carries them? Otherwise I'll be begging for one on here 'cause you don't see these trucks in the JY's out here anymore. Thanks again! Will- Quote Link to comment
datzenmike Posted March 18, 2009 Report Share Posted March 18, 2009 Do you see the middle hose on your broken TVV that should go to the vacuum advance? Do you see that it comes out to a tee and back to the white Vacuum Control Valve? The hose is missing off the bottom of it IMG]http://i141.photobucket.com/albums/r66/driftingouttosea/Nissan_720/PICT0172.jpg[/img] The bottom hose on the Vacuum Control Valve should go to another tee and from there to the carb AND the vacuum advance on the distributor. Quote Link to comment
lostinthe202 Posted March 18, 2009 Author Report Share Posted March 18, 2009 Good eye, yes, it's missing 'cause I unplugged it to change the line. Hopefully after I change everything I'll be set Quote Link to comment
KELMO Posted March 19, 2009 Report Share Posted March 19, 2009 Will, Didn't see this post until after I posted in your other one but...... Part # 14890-N8500 around $25.00 don't know for sure if it is a dealer item only. Kelmo Quote Link to comment
lostinthe202 Posted March 19, 2009 Author Report Share Posted March 19, 2009 Thanks for that info and part number Kelmo! Good to know it's still available. Will- Quote Link to comment
lostinthe202 Posted March 23, 2009 Author Report Share Posted March 23, 2009 Okie dokie, problems solved! I replaced all the vacuum hoses and the idle went up! I check for proper operation of the 6 million things that can act on the throttle and everything seemed free moving. I then simply turned down the idle screw. My theory is that the vacuum leaks had caused a rough or no idle and someone turned the idle screw up to compensate. I dunno, don't really care since it's working. Also changed the bad U joint ( I'm amazed it didn't break when I drove it home cause it was haaaaaamered) so now I'm ready to rock! Thanks again for your help. Quote Link to comment
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