Hey guys,

Im asking on behalf of a friend who has a 91 3.1 V6, his car has developed a knocking / clattering noise under load, and also a big loss of power !

He says its ok just idiling though.

Im going to his tomorrow to have a look at the car with him so i was hoping someone could point me in the right direction with whats potentially wrong with it. I was thinking maybe one of the rocker arms is loose causing the noise ?

 

Check the fuel pressure... The knocking is probably spark knock due to leaning out of the fuel mixture and the loss of power goes with that AND the fact that the ECM is retarding the timing to prevent the engine from blowing its top...

Pull a couple of plugs to confirm. Plugs should be clean (but not brand spanking new clean) and undamaged. Fuel pressure should be no less than 37 PSI (about 240 kPa).

 

Well we never checked the fuel pressure as ive got no gauge and neither has he, but another friend turned up whos really good with engines and straight away he said its a failed hydraulic lifter, more investigating required i think

 

One thing i noticed after stripping the engine down, we took the distributor out and there were quite a few metal filings stuck around it.

Would this mean it might not be the hydraulic lifters after all, and might be something more serious relating to the shells or camshaft etc wearing away ?

 

pull the valve covers off & inspect for loose rockers & such

 

Already done that, the whole top of the engine is off, rocker arms were fine, rods are fine, hes ordered new rods and lifters anyway now that the engine is apart he was just a bit concerned with these metal filings around the dizzy when he took it out

 

ok guys, hes installed new hydraulic lifters and pushrods, put everything back together and,......oh dear, it sounds 10x worse, i went down just before he started it up so i took a little video.

It sounds like there is no oil in the engine ! when obviously there is, all parts where lubricated with that red super slick stuff upon installation. Another friend who was there too thinks that he possibly hasnt set up the valve lash properly or that the galleys are blocked ?

any advice appreciated guys

 

Valve lash should be between 1/2 and 3/4 turn after play is removed. And yes, I know that most service manuals state different, but this was proven with a compression gauge...

 

I agree with mav. I have had to lash in my valves at least 7 or 8 times over the last few years. Never have I had a issue when I go 5/8ths of a turn after the play is gone. Its a important step in putting it back together. If its not done right you could have to take it apart to either tighten them up more because of the chatter and valve issues, or because you bent a pushrod from over tightening it or even mess up the lobes on the cam.

Did he lash those puppys in when the valves were all closed. Takes a good 30 minuets to do it right because you have to get every valve closed to do it right so that there isnt already force on the pushrods.

 

Thats exactly what he done yeah, felt the rod until there was resistance as normal, then turned the nut 3/4. So it sounds like he has done the valve lash right then ? I dont know if he done them in regards to being open and closed etc, i think he did say he made sure it was TDC and done it as per the manual

 

Well, then the only thing left to do is to hook up an oil pressure gauge (mechanical) and make sure there is sufficient oil pressure. Unless he would rather get the engine off of the mounts and pull the oil pan off to make sure there isn't anything obstructing the oil pickup screen.

 

Did he adjust them with the EOIC method?