Does this cam and valve gear sound normal? - Ford Forums

EA S · 08-16-2001, 19:29

Took the rocker cover off my 3.9mpi for first time last night. My experience to date is with pushrods and I haven't seen inside Ford OHC before so don't know what's normal. I found:

- Everything covered in dark reddish/brown varnish, except contact surfaces of rocker rollers and cam lobes (Could this be from fuel? I have low compression in one cylinder and wonder if an intake that not's fully closing could be passing fuel into rocker area).
- Rocker rollers all shiny, but some fine lines in them which almost look like grit had been there.
-Cam lobes not all shiny - shiny contact lines with varnish sections, so not making full or even contact with rollers.
- Cam lobes on No1 intake and exhaust have very noticeable pitted line in centre - maybe manufacturing fault.
- Tops of pedestals have moderate encrusted carbon.
- Inside of rocker cover has light/moderate encrusted carbon.

Apart from the obvious faults with the pitted cam lobes, is all this pretty much normal for a motor with 119,000km?

Aussie Pete · 08-18-2001, 00:07

Quote:

Originally posted by EA S
Apart from the obvious faults with the pitted cam lobes, is all this pretty much normal for a motor with 119,000km?

Compared to what I've seen at my mate's engine reco shop, you've got a good one!

08-18-2001, 00:24

Quote:

Originally posted by EA S

- Everything covered in dark reddish/brown varnish, except contact surfaces of rocker rollers and cam lobes (Could this be from fuel? I have low compression in one cylinder and wonder if an intake that not's fully closing could be passing fuel into rocker area).
- Rocker rollers all shiny, but some fine lines in them which almost look like grit had been there.
-Cam lobes not all shiny - shiny contact lines with varnish sections, so not making full or even contact with rollers.
- Cam lobes on No1 intake and exhaust have very noticeable pitted line in centre - maybe manufacturing fault.
- Tops of pedestals have moderate encrusted carbon.
- Inside of rocker cover has light/moderate encrusted carbon.

Apart from the obvious faults with the pitted cam lobes, is all this pretty much normal for a motor with 119,000km?

A faulty inlet valve wont give you low compression, nor will it let fuel into the rocker cover, fine lines on the rockers are o.k these can be attributed to the bedding in process, although you dont describe how fine they are.
Your cam lobes suggest to me that with the pitted line in the center they were'nt ground right when the engine was put together. Lobes must rotate in the lifter bore to achieve there purpose. Yours sound like they are sticking and riding the tappet. need some more info on the crust you talk about, but have to agree with Pete I have seen worse engines thasn this come into the shop, and with more problems. Consider yourself in the top 10.

batbo6 · 08-18-2001, 05:26

Actually I'd guess that the crusty build up has been caused by lack of maintenance(ie oil changes at the right time) or the use of a non detergent oil. The pitting on the lobes would follow if the oil is inferior or hasn't been changed at the recommended intervals.
Clean healthy oil is critical and a very cheap insurance policy for a long engine life.

XR_Strider_GuY · 08-18-2001, 07:46

Yeah your engine sounds spot on. Shouldn't be a problem.

IMO if you want your engine to run cleaner chuck some oil flush in her and then use Mobil One.

EA S · 08-19-2001, 18:50

Thanks all.

Nice to get good news, and unanimous at that!

I think all the comments were spot on.

I think the carbon is just cooked on oil sludge.

I'll have a look at the lifters on the pitted lobes and see if they're stuck. As it's only on a couple of lobes I suspect that it's more likely to be that than bad oil, which I'd expect to affect all or most of the lobes, but bad oil is certainly a possibility.

The previous owner hadn't heard of oil changes, judging by the sludge in it when I got it. Maybe he thought he didn't need to as he was probably putting in a sump full every few months anyway, given the evidence of huge and long term oil loss that the dealer's steam clean didn't reach. I'd guess it was coming from the timing case and rocker cover.

I've flushed it all out and wasted a couple of filters and some good oil with short interval changes and the oil's staying clean now, like it should. I always change oil every 5,000k so it'll stay OK.

There's no serious oil leaks now. The dealer must have fixed up the timing case cover, which was freshly sealed when I got it. I'll put a rubber rocker cover gasket on and that'll cure the seepage from there.

The last owner, and the dealer, probably thought it was a dog but it's actually a bloody good car, with immaculate interior and excellent exterior, and nothing serious wrong elsewhere. I've done a couple of thousand k's in it and anything serious should have popped up by now. Here's hoping, anyway.

Kieron · 08-20-2001, 22:40

Quote:

Originally posted by THE DOCTOR

A faulty inlet valve wont give you low compression, nor will it let fuel into the rocker cover, fine lines on the rockers are o.k these can be attributed to the bedding in process, although you dont describe how fine they are.
Your cam lobes suggest to me that with the pitted line in the center they were'nt ground right when the engine was put together. Lobes must rotate in the lifter bore to achieve there purpose. Yours sound like they are sticking and riding the tappet. need some more info on the crust you talk about, but have to agree with Pete I have seen worse engines thasn this come into the shop, and with more problems. Consider yourself in the top 10.

Now this reply has got me a little confused :confused:

A dud inlet valve could cause low compression if it doesn't close properly.
The engine being discussed is tha Falcon OHC and the rockers use a roller running directly on the cam lobes, the valve lash adjuster sits on top of the valve stem on the other side of the rocker.

Kieron

EA S · 08-21-2001, 00:15

Kieron

Your point about the intake valve not closing was what I had in mind, on the basis that the chamber doesn't seal fully and lets some out on the compression stroke.

I was also thinking that with compression pushing air above a partially open intake valve the stem seal might eventually get damaged and tiny amounts of fuel vapor might get pushed up past the seal into the rocker area and over time cause the reddish brown varnish I found, if it was fuel dye. If so, this would indicate a sticky intake valve rather than exhaust. On thinking it through a bit further, the problem with that theory is that if it could push that hard, wouldn't it be interfering with the incoming air/fuel charge fairly significantly and cause rough running in at least the cylinder with low compression, and maybe stuff up the readings from the air density sensor by obstructing airflow / airspeed and so interfere with engine management?

You are correct about the lifters not being on the cam. I'd already noted that the rollers were on the cam. I can only plead a Force 8 hangover yesterday and a few hours' sleep the night before for not picking it up. My mental picture of the valve gear was a bit fuzzy, along with a few other things. I think The Doctor's reference to lifters (although he said lobes) rotating in the lifter bores indicates he was thinking of a pushrod, although when I read it yesterday I quite happily turned the rocker arm through 180% and formed a mental picture of a non-rotating lash adjuster sitting on the cam and grinding a groove in it, which I was going to check. How dumb was I?