Knock,Knock,Knock

[carolinaturbo]

Hey Guys I need help troubleshooting a Knock. When I get on the car It starts to make a noise at about 10lbs and up. Anything lower its aok. It sounds like some one is hitting the top of the piston with a hammer. The knock on the scanmaster goes through the roof. I have done a spring cleaning with all the normal maint stuff. I checked the comp on all the cyl they seem ok. Just a little low on the #6 cyl.ABout 90psi on comptest. rest all around 160psi. Any ideas. Please help.

 

[turbocam]

low

you may have a bent valve

 

[dproberts05]

low

Or one of your valves could be open in that cylinder.

 

[turbofabricator]

You most likely have a fuel delivery problem, as in fuel pump or filter. What fuel pump do you have? What fuel presure are you seeing at 10 psi boost? You sound like you are detonating REAL bad. STOP driving the car until you get this sorted out, or you will be buying head gaskets, or ALOT more.
You might want to take it by a local Turbo Buick shop and give them a ride.

 

[carolinaturbo]

I have a walbro pump with hot wire kit. I dont know the fuel psi at the knock time. What would be the spec on this and whats the best way to check it?

 

[87granny]

what injectors are in it and how old

 

[carolinaturbo]

I have the factory ones in it. Have 140,000 on the engine.

 

[87NAT]

You have a low cylinder...start there. Its time for maybe a leak down test on that particular cylinder. Bent valve, blown headgasket, etc....

Turbofabricator is correct..stop driving the car until you find the source of the problem. "Hammer hitting piston" noise is not good.

A good investment for any TR owner is an aftermarket fuel gauge. I have one on a 3 ft line under my hood. I leave it ziptied next to the windshield wiper bracket almost all the time. BUT...if I need to see what my FP is doing at mid to WOT I just slip it under the hood and use velcro to attach it to my windshield. That way you can rule out any fuel related issues.

 

[carolinaturbo]

Thanks Ill try that. Is there any procedures for a leak down test?

 

[SHADOWII]

If you don't ...

have the test kit, you can purchase a cheap one from places like harbor frieght and such for <$4o.oo. I believe the instructions are in the kit. If you want to make your own, do a search, there are instructions in this or gnttpe.org