Bent Pushrods

tonyh

New Member
I recently spent a small fortune having my P6 recomisioned, the garage got it thru the MOT, but said the noisy tappets were down to a worn camshaft. I have a workshop manual, so set about the work myself, I purchased a new camshaft and lifters, after stripping, found a broken pushrod, after a thorough clean I started putting it all together. upon starting, I found I had no oil pressure, I stripped again, cleaned the rocker shafts inside and out, and reassembled. This time the oil light went out, then the pressure came up, however after warm up, and slight revving, the tappet noise was back. I stripped again, and found a different pushrod had bent. I tried again, and the same thing, but a different pushrod. I purchased a pair of new shafts, and sixteen alloy rockers, and re assembled making sure the rockers were in the correct order, and the shafts positioned correctly. on start up, sounded great, left to warm up on idle, then a test drive. Unfortunatly, after about half a mile of normal driving, it happened again. Any ideas? why am I bending pushrods?
 
Hi
Had the same problem when I started up a engine after long term storage .
Found engine valves sticking and causing piston to valve contact.
Removed rocker shafts and checked valves for full movement ( made sure piston is at bottom of bore ).
Also did you replace timing chain and gears when fitting camshaft?
The nylon cam gear wears so much they can shear, and or chain jumps.
Clive.
 
Also forgot to mention about oil pressure issue.
Was the sump removed to check pick
up strainer and debris in pan?
Lack of servicing will cause this. Also the crud in sump will jam oil pressure relief valve leading to pressure problems.
Clive.
 
Silly question. Did you check the lifter endfloat and shim the rocker pedestals?

If everything is standard there shouldn't be any need. If they are standard parts but still need the preload setting then they must be cr*p parts.
 
Originally the top was put back together using original parts, then new shafts and rockers were purchased, original part N0s, so I presume standard parts. The new cam and lifters are also standard, they were purchased from a well known P6 parts specialist, so I would think they wouldn't sell something that's rubbish ????
Yes the sump was removed, cleaned, and replaced, the strainer also. By the way, I had to move the car yesterday evening, started first time as usual, and no noise, seems strange that it only happens when warmed up.
 
Y0u´ve run across a little nightmare, I think. What you´ve done sounds like you know what you´re doeing. But, what´s about the timing components. You have made all new, but I cannot read anything about these components, which should also be renewed, when a new cam comes in. The timing cover with the oil pump was off, so depending on the cleaning process, did you prime the oil pump gears before reassembling ? Did all the lifters come out smoothly or with some "help". Anyway, spark plugs out and check, if cyl. no 1 and TDC mark on your pulley is ok. If your pushrods (new rods ?) are hitted, there must be something with a worn chain, wrong position. Sorry for that question, but timing at 650 rpm is ok ?
 
When you installed the new cam did you: -

1/. Soak the new lifters in oil overnight prior to fitting, to help them fill up?

2/. Prime the oil pump before starting? You can do this by packing it full of petroleum jelly, or taking the distributor out and spinning it up with a cordless drill, or both.

3/. Use can lube on the cams and lifters when fitting?

4/. Manually turn the engine with inlet manifold off, to check nothing was binding? i.e. valves, rockers, lifters, etc.

5/. Run the engine at 2,000rpm for 20 minutes to help the new cam bed in?

Richard
 
When you installed the new cam did you: -

1/. Soak the new lifters in oil overnight prior to fitting, to help them fill up?

2/. Prime the oil pump before starting? You can do this by packing it full of petroleum jelly, or taking the distributor out and spinning it up with a cordless drill, or both.

3/. Use can lube on the cams and lifters when fitting?

4/. Manually turn the engine with inlet manifold off, to check nothing was binding? i.e. valves, rockers, lifters, etc.

5/. Run the engine at 2,000rpm for 20 minutes to help the new cam bed in?

Richard

Correct. All absolutely vital to do. Mine hadn't run since 1982, wasn't seized but the vendor turned it over and bent a pushrod. I went for new cam and timing gear, lifters, push rods deep clean of rockers, uprated oil pump (best v8 mod available) and had valves Reground.
 
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