Disco 3.5efi problems since new cam

[robp]

Hi Rob,

Long time no see!!

Im back from AbuDhabi on the 7th of Dec, I could pop round and have a look if you haven't had a chance by then...

Andy

Hi Andy,

Fancy meeting you here!

Cheers for the offer fella think I might have found the issue though

Did a bit of diagnosis today. Followed Ramon's advice and pulled the plug leads one at time whilst noting the RPM. Cylinder No1 made no difference at all but all the others made the RPM drop by 90-100rpm.

Checked the timing and swapped out lead no one wih no change.

Took off the rocker cover to find massive movement in the first rocker and pushrod. Looks like follower No1 is at fault then!

Going to order up a new set of followers, cam, gaskets etc and change over again. The pushrod on No1 also looks a bit flattened on the end where it has been rattling around. Should I change all 16 or just the one? Also the cup of the rocker arm that it sits in is showing signs of damage to the edge, again where the pushrod has been banging around.
Same question again change the whole lot i.e. shafts and rocker arms on both sides or just the one arm that is damaged?

[ramon alban]

Followed Ramon's advice and pulled the plug leads one at time whilst noting the RPM. Cylinder No1 made no difference at all but all the others made the RPM drop by 90-100 rpm.

Hello Rob, I'm very interested in the results you observed, as my test procedure was put together using anecdotal and actual experiences taken from a small number of V8 owners - not including me!

The "rpm drop" figure that I was expecting from a "good" cylinder was deemed to be around 250 rpm, but your results say that should be more like 100 rpm.

My expectations assume that the engine is in otherwise perfect condition and also that it is well warmed up.

However, from your earlier post, it seems that your original cam and lifters were pretty much bujjered so is it possible that the rest of the engine is also well worn and with such low annual usage, perhaps the rings are somewhat gummed up, making the results you found not typical.

Any light you can throw on the state of your engine and the way the tests were carried out will aid me in assessing the efficacy of the procedure, as written.

Cheers - Ramon

[robp]

Hi Ramon

I wouldn't be too concerned about the results I got not being "normal".

My multimeter didn't do RPM so I picked up another one from Maplins.

This one used an inductive pick up for the RPM measurement which I was not confident about. I would have prefered to take the feed direct from the tacho feed on the alternator for accuracy.

I warmed the engine up for about 10mins without the viscous fan attached as I was also checking the timing.

It settled down to a steady 800rpm before I started the testing. Whilst the rpm drop was not what you were expecting it did accurately show that No1 cylinder wasn't right, so in that respect I am very grateful for the guidance.

The engine has done 65k miles although only about 5000 in the last 6 years. I can't say what the piston rings are like at the moment. I have ordered a compression tester and aim to check that. Not sure though if the results will be affected by the knackerd follower as the first valve on the left had bank obviously isn't opening correctly.

[ramon alban]

Thanks for the feedback, Rob, I'll leave things as they are then, because the process actually works fine, as logically it should. Perhaps the actual rpm results also depend upon other factors such a compression ratio, timing, fuel supply system (efi/carb), oil viscosity, torque converter load (auto), etc. A veritable minefield of variables! Ramon

[kiwicar]

Hi
are you planning to just replace the cam and valve gear or doing a strip and rebuild?
Just if you have now had 2 cams and tappets dump iron filings into the oil as they have destroyed themselves have you thought what the main, big end and cam bearings will be like and how much swarf will be in the oil galleries?
I would drop the oil as I surgested earlier and see how much swarf there is in the oil. I would also take off a main bearing cap and have a look at that to see what state it is in. If you just keep running swarf suspended in oil through new cam components you will never bed them in, just wear them out. You really need to get the oil galleries clean of metal particles and check the rest of the engine components.
What valve springs are you using by the way?
There is an article in car craft magazine from last year on a 400ci chevy small block where they wore out 2 lobes on a cam (over 10 thou off the nose of each lobe) in the brake in process by having too heavy valve springs for a flat tappet cam. ie worn out cam in under 20 minutes on no load. On top of that the swarf destroyed a new set of main, big end and cam bearings and damaged the main bearing surfaces badly enough to need a regrind.
I don't think just replacing the valve train is the answer.
Best regards
Mike

[DaveEFI]

Surely the oil filter would stop swarf getting to the bearings?

[BanditSid]

I've seen the cam running in process mentioned on a few forums, did Rover do the same thing in the factory with new engines ?

[kiwicar]

Surely the oil filter would stop swarf getting to the bearings?

I wish!
Oil filters have an over pressure bypass valve in them that when they begin to clog let the oil straight through! generally these fail well before you change the filter and just bypass the filter all tha time.
Even then you should consider what the swarf is doing to your oil pump (which is up stream of your filter).
I wish you could rely on the filter, then you could just chuck the engine together and rely on the filter to remove all the grot, save hours on cleaning parts (and pretending that you haven't "been using the dish washer again")
Also just look in the bottom of your sump and see the swarf in there after 50k miles or so on an engine that has had no major "problems" how do you gaurentee it isn't being splashed all over the crank area. Finally anything that wears off the inside of the tappets or tappet bores can only exit the engine to the sump via the main bearings on the crank (have a look at the oil gallery system for the rover or practically any push rod V8).
This is why I keep banging on about the coffee filter routine it tells you so much about what is actually happening inside your engine!
Best regards
Mike

[kiwicar]

I've seen the cam running in process mentioned on a few forums, did Rover do the same thing in the factory with new engines ?

No they did not

(but they did not leave them running at idle when first started)
1/ because when these engines were made there were much higher levels phosphorous and zinc in oil.
2/ how long is range rover engine warrenty? 1 year 12,000 miles? you can hold a customer off on a "rattle" from the top end of the engine for quite a while. . . oh yes sir nothing serious, they all do that. . . it is just them bedding in. And yes a few years ago on this forum we did bave a chap who had been given this routine about his range rover untill it was well out of warrenty and then he got charged for an engine swap!
Best regards
Mike

[DaveEFI]

I've not experienced it, but have been told if the filter gets blocked and goes to bypass mode you get a noticeable drop in oil pressure.

My feeling is all this about running in a cam is over hyped - to say the least.

I've changed loads on RV8s over the years and simply have made sure it's well soaked in oil before starting. As you'd do with any bearing, etc. And then just driven it normally. I can't be certain how long they subsequently lasted - but it's more than a few hundred miles, as in the case of Rob.

Of course if I'd bought a new cam kit with special running in grease or whatever I'd use it.

[robp]

Mike.
Thanks for your help so far (and everyone else who has contributed)
At this point I was planning on new cam and followers. I did ask about the rockers arms and shafts as one arm looks a bit dodgy where No1 push rod has been banging around.

Nothing about the valves springs or cam had been changed from standard as far as I know. Certainly not in my ownership and I have no reason to think they are anything other than standard.

Stupid Question No 42
You talk about taking off the main bearing end cap. I presume this is an engine out procedure? If not whats the process?

Stupid Question No 43
Is there an easy way to clean the oil galleries out whilst the engine is in situ?

[kiwicar]

Hi Rob
Answer to Q42
you can drop off a main bearing cap with the engine in by dropping the sump and and unbolting a cap. I would pick one in the middle as there are fewer gaskets to disturb.
Answer to Q43
No you need to strip the engine to get at all the galleries and get all the gallery plugs out.

Dave
The oil pressure does not change when the filter bypass operates, if you fitted the version of the oil filter without the bypass and over-pressured it then you would at some point get a sudden drop in oil pressure as you force the paper filter material into the galleries . . . seen it done on a hilman imp engine oh that is why that version of the filter is half the price!
Best regards
Mike

[robp]

Did some further investegation today

This is the offending cam follower



You can see that the top cup has actually spun round!

As a result of it knocking around the bottom looks this


The good news was that after dropping the oil and running it through the filter there was no metal in it.

Cheers for the advice so far