Finally got the vp44 plumbed, primed, bled, and wired. As my son was cranking the engine to bleed the hp lines, I got this psssh, psssh, pssssh noise....

Now, I'll let you know what isn't done yet on this 'several fixes at once'

Intake is still open to the world. Air horn is not there, along with any form of intake pipe or turbo.

Radiator is not in,

steering gear is not in, Lines are dangling from the pump. I did allow the engine to 'fire' for a couple seconds after tightening the hp lines....just to confirm my 'new' pump is a runner... and that part is good.

Back to the weird noise: I would swear the noise is coming out the intake plenum... At least that side of the engine and/or front of engine. It's definitely equal spaced... Like 1 phssssh per 2 revolutions. My thought was at first; bad or out of adjustment intake valve, and without the air horn in place, I can now hear it.

Or another scenario: I got a bad spot on my vacuum pump seal, and since I didn't allow the engine to start, I could hear it leaking? there was noticable blowby on just cranking speed. (it was clear clean air since the engine wasn't actually running) I only noticed it because I put my thumb over the tube. It took about 5 seconds to feel the pressure (slight, but still there... I'd guess 1-2 #s) It was a smooth flow... no puff puff puff..

Or... and I am being really hopeful on this... it's the way one injector line could be 'resounding' on the sheetmetal lid of the intake..

Truck has 135k miles, and I'll run the valves tomorrow..

Anyone care to jump in here?

Thanks!

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.....ran the valves this morning... most were a tad loose. No tight ones.

hooked up the air horn and downpipe-to-the cooler and refired the engine. I can hear the phssssh through the intake tube.

Head gasket.

How about the intake gasket? A pshh sound to me would either be air of fuel. The fact that it isn't constant make it sound more like fuel. If it was a head gasket I would expect to see coolant.

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How about the intake gasket? A pshh sound to me would either be air of fuel. The fact that it isn't constant make it sound more like fuel. If it was a head gasket I would expect to see coolant.

IMHO, you don't have everything connected up.................you're gonna hear noises that are different than if you had everythging buttoned up like it should be!!

True on the different noises coming from unbuttoned components..When I crank the engine with the vp unplugged, and put my ear down by the air tube (where the heat exchanger would hook up)...I'll hear this: duh,duh,duh,duh,duh,phsssh,duh,duh,duh,duh,duh,phsssh etc etc.. Notice there is 5 'duh' and 1 phsssh. methinks I have an intake valve(s) issue. I truely thought I'd find a 'tight' valve this morning during the valve set. All were just a tad loose. I think if I'd had a simple head gasket trading compression between 2 cylinders, I'd have a noticeable miss in the exaust.... which sounds as smooth as a sewing machine. So, I'll fashion up a leak down tester and hit each cylinder at TDC, should hear the leak through the intake. Dagnabbit. This week's already shot to @@#%, It's only Sunday too! And it's supposed to snow again tomorrow.One 'known' about this engine, about a year ago, the wife was driving it when the belt broke, and it got REALLY REALLY hot. As in pegged. There might be something tied with that.

sure nothing dropped into the intake plenum and is hanging a valve open? i would be wary to run it until you figure out what it is.

sure nothing dropped into the intake plenum and is hanging a valve open? i would be wary to run it until you figure out what it is.

+1 Possibly something holding a valve open?

anytime i have any plenum open i always stuff a rag in it to ensure NOTHING gets in there.i would take that while plenum off and inspect each valve somehow.

^^^Thats a good thought about something possibly being in there but I dont think its possible it could be actually hanging a valve up or he would have noticed something a miss when he adjusted his valves.Ive never tried to crank my engine with out everything tied back together, are you positive something's not right? Engines do make mystery noises, my 650cc single cylinder thumper really rattles the valvetrain if you get right down by it and everythings within specs.

rag was stuffed immediately upon disassembly, and a thourough check for loose parts/debris before starting/cranking a unfiltered engine. I had this thing sanitized before cracking it open.99% certain nothing was sucked in during this check. LOL Hey, I've never had the top off the plenum.... what kind of view is there into each port? Can I see at least the first valve stem? I got the injectors out, and will hit each cylinder with simple compressed air and a rubber tipped nozzle to pressurize.. If I find a sizzler, I'll activate that valve a bunch and see if It dislodges a foreign body..

Not sure if you could get a mechanics mirror down in there to look around a little before tearing it down further? Whenever I start hearing funny rattling noises I hold my head still for a minute and they usually stop.

you may have a valve over specced allowing it to vent and not fully close. id recheck tolerances seeing that you are positive nothing is in there.first part of troubleshooting, if it wasnt broke before, what did you change to make it broke

was the truck in running condition before starting these projects? How come your trying to prime the system if your not ready to start the engine? more then likely you will need to run the engine to finish the prime and have it run smoothly.