Hey everyone,

1999 Disco 1 SD V8 4.0L

just replaced the: head gaskets, valve stem seals, hydraulic lifters, rocker cover seals, spark plugs, oil change

Had the heads milled and cleaned. Valves were vacuum compression tested. Rocker arms were cleaned by the machine shop.

everything back together, no codes, but a distinct lifter sound on the driver side that is louder at one point by stethoscope than all the other points when listening on the rocker cover. I’m going to pull the rocker cover and run it with the cover off, but any ideas what could be going wrong?

i know this lifters don’t need adjustment. My guess is a bad new lifter, bent rod, or something with the rocker arm?

thanks

 

I'd leave it alone and drive it or run it a bit. Whenever an engine is torn down it takes a bit of time for oil to get fully up and coating everything. If you didn't replace the rocker arm assemblies you could have a loose cup. I've seen them come loose after the rockers are fully cleaned (oil gunk was basically holding them in solid).

 

thanks for that, Really haven’t done a lot of driving yet, only about 10 minutes. The sound seems to diminish at higher speeds but comes back as soon as I slow down.

i didn’t replace the rocker assembly, just cleaned.

 

Yep out of all the rebuilds/engine repairs I've done the engine first gets oil pressure, and after that the engine will get better sounding the longer it runs and a few cycles is usually enough for the oil to get everywhere it's needed and the engine will then quiet down. The rocker arm thing is pretty common after a really good cleaning. I've personally got into cleaning them just enough to verify oil flows thru them but making them look absolutely new = I avoid now. My 97 XD 4.0L was completely silent when I bought it. I had it about a year and the HG's finally went from a seep to full on external leaking. I tore the engine down, and deep cleaned all the rods, rocker arms, and heads. I then put it all back together and once it warmed up I had a nasty chirp/squeak. It only started making noise when the engine was at temp. I went on a trip and on the way back it was just a constant chirp/squeak from the valve train. I got home and tore into it when I had time and found 4 rocker cups completely loose on bank 1 rocker arm assembly. I had a spare set and I verified they were good and put it all back together. She's been silent ever since and I've put close to 10K on it since the HG job.

95 D1 also got a HG job after I bought it and upon startup she was loud. Then it got quieter the longer she ran. Several runs up to temp and she was all good. The only noise I hear from either = aftermarket Volvo/Ford Fuel Injectors which are louder vs the stock Lucas Fuel Injectors.

 

I assume if that is the case with the rocker cups it’s more just loud and annoying and not a huge problem for operation?

 

Yep they're moving around vs being held in place making noise. You can usually grab a set off an 03-04 D2 at the junk yard pretty cheap and just swap em out.

 

thank you! Odd, didn’t know an 03-04 D2 would work with a 99 D1

 

You can use the rocker arms out of any LR 3.9/4.0/4.2/4.6 engine. Only thing that really changed was 14CUX dizzy setup with fuel injection, to GEMS, and finally the BOSCH setup. Intakes, fuel injectors, and stuff like that changed, but the guts of that engine = pretty much identical minus a few things like cams geared for a dizzy or cams for non dizzy setup, front covers different for same reason, CPS sensor mounts, and a few other changes but block wise and internals = you can swap stuff or use stuff from other years no problem.

 

My 96 4.0 GEMS had noise after rebuild. Sounded just like valve tick. I finally tracked it down to a vacuum leak between upper and lower plenums. But that was after I got a new set of rocker arms and rocker shafts out of the deal (new rockers are easy to get, and the work is fairly simple).

 

Drove for an hour last night without issue. This morning I drove for 20 minutes and then it threw two codes: P1316, P1317. “spark plug voltage detection” one code is for the right hand bank and the other code is for the left-hand bank. “Circuit Malfunction”

Would this be the coil pack, because it is on both sides? The engine started misfiring after this. Thanks