Water pump causing phantom knock?!

[sonicnofadz]

Ok after enjoying a good month of not having any type of phantom knock, its back again only much much worse. I cannot rev the engine past 3000 rpms without spiking up to 43 counts of knock. It knocks going into boost, knocks when in vaccuum. I know I don't have any boost/vaccum leaks. Around this same time I think my coolant light started coming on intermittently. My coolant level is FULL, there is plenty of coolant in my system. Could perhaps the worn bearings of the water pump be causing this phantom knock? I have an SAFCII running 650s cc injectors and EVOIII16G (knock sensor is brand spanking new). No amount of fuel addition/subtraction is making this knock go away. I run things lean, run it rich, it doesn't seem to make any difference. I also have revised 3G lifters....anyone have ANY ideas?

 

[out there]

i've heard of worn bearings causing phantom knock, perhaps you should check into it... how old is the water pump? time for a new one?

 

[sonicnofadz]

As far as I know the pump has never been replaced (its the only thing that hasn't been replaced in my entire engine bay). I think this may be the cause of my problem...I can hear some kind of weird "whirring" sound coming from that area near the timing belt. At first I thought it was a pully scraping against the plastic timing cover but I listened closely and it sounds sort of like a grinding sound. Sigh....timing for a new pump I guess. Its so strange that this could cause knock...argh my car pulls like a honda now!

 

[DaveT]

Sounds exactly what I am experiencing. But I do have a new water pump assembly. I can't figure out what the problem is and it has been since Febuary.

Please post what you find when/if you replace the water pump. I am curious to see if that fixes the knock.

DaveT
92GSX

 

[sonicnofadz]

Hmmmm....yeah I'm gonna replace the water pump and see if that does the trick. The only thing else I can think of is that maybe I broke a lifter and its causing excess noise/vibration. I'll also take off the valve cover to reinspect the valve-train. ARGH

 

[DaveT]

Does it knock in nuetral, free reving?

DaveT
92GSX

 

[sonicnofadz]

You know what I have only tried once, and nothing happened, but I did rev it that much...Ill try it again tonight and see what happens. It would make sense that if the water pump was indeed causing the knock that it would knock in neutral....

 

[sonicnofadz]

I took it out driving around DC today but before I set out, I free rev'd it a couple of times. Free reving really quickly to like 4-5k produces no knock. If rev it really hard to around 6k-7k some little blips of knock show up, but no where near the amount I get when running around 30mph at 3-4k. So maybe the water pump isn't causing the knock, and perhaps I have a weird boost leak somewhere? Or maybe a fuel delivery issue? I fiddled around with the injectors (maybe they were leaking air past the orings into the intake) the pcv valve, just about any fitting that connected to the intake manifold. Once I did that, I took it out for a drive and things almost seemed normal for a while! I did a couple of pulls and I didnt even get any knock. Weird. Then it started to come back, and now I get a flat constant plateau of 43 counts of knock whenever I go into any boost. WTF.

Maybe its the PCV valve running off the valve cover? If that thing is broken, it will constantly suck it air from the valve cover (boost leak/vaccuum leak). I'll try plugging up that hole and see what happens...there does seem to be some type of hissing sound coming around the intake manifold area, but I cannot pinpoint it. I just swapped in two new throttle (oem) throttle body gaskets, and the hissing doesn't sound like its coming from the throttle body. Who knows.

 

[DaveT]

That sounds exactly what mine is doing and I can't figure it out. Still could be a boost leak somewhere. I do have a breather catch can, intake port is capped and still get knock. Do a vacuum test to see if you have any boost leaks first. Then go from there. I'd hate to see you sink money into a water pump and it not fix the problem.

DaveT
92GSX

 

[sonicnofadz]

Yeah I have a catch can/filter too...but I've had that for a while now and had no problems with knock until about 4 days ago. ARGH. The water pump needs to be replaced anyway, my car is almost 14 years old, and has about 102k on the clock. Im sure the pump is on the way out. I just wish I knew what the hell is causing this problem! I'm CERTAIN the water pump isn't the problem. If it was then I should be getting TONS of knock when I just free rev it in neutral. Maybe my stock fuel pump can't keep up anymore? Boost leak? Something just loose and rattling around? Who the hell knows. Gotta love these cars

 

[sonicnofadz]

Ok, the knock is finally under control somewhat! I've been doing some reading on partial throttle knock (search for "part throttle" in the forums) and found some interesting info...in one thread someone mentioned that they had to richen things up by at least 5% the whole way down there fuel curve because of the sudden change in temperature (fall). It recently has gotten REALLY cold around my area all of a sudden, and I thought that this might be my problem. I also noticed that even at idle my o2 voltage was REALLY low, like around .5-.6 and lower. So I gave everything like around %5 more fuel at all rpms, and noticed my o2 voltage now stays in the .85-.9 range and everything runs (and even sounds) alot better! This means I was running pretty lean this whole time, hopefully I didn't damage anything. Keep in mind I'm also running 650 injectors on an otherwise stock fuel system. My fuel pump is even stock, so I am sure Im getting some knock due to a low stock fuel pressure (too low for these big injectors). I'm only running 10lbs of boost right now though, so it should be ok until I get a walbro 190. Thanks for everyones input, hopefully this info might help someone else out in the future...