Death-to-a-cam

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Discussion

tofts

Original Poster:

411 posts

155 months

Wednesday 9th November 2016
quotequote all
Picture says all really!

In for a 12k, was working through valve adjustment and found this.

Engine has been "rebuilt" but a retaining spring/washer has either been omitted completely or its fallen off. Latter seems unlikely.


Potential engine death in the making, caught in the "not toooooo late stage"

m4tti

5,426 posts

154 months

Wednesday 9th November 2016
quotequote all
Which spring washer are you referring to?

Would like to know. Have a head on the bench.


tofts

Original Poster:

411 posts

155 months

Wednesday 9th November 2016
quotequote all
Ah of course, couldn't remember if it was meant to be a spring or a washer/shim.

Can't quite get the angle, but there is an obvious gap between the finger follower and the head, meaning it can move side to side about 5mm.

Your pic shows no gap and thus no movement and therefore correct! Will try to get a better pic tomorrow with a mirror.

Edited by tofts on Wednesday 9th November 23:05

m4tti

5,426 posts

154 months

Thursday 10th November 2016
quotequote all
You can see the upper most spacer in your pic between the head and the follower. It has a chamfer on the outer edge giving the illusion there is a gap.

Was it a factory rebuild.

tofts

Original Poster:

411 posts

155 months

Thursday 10th November 2016
quotequote all


That gap!

unkown rebuilder.

m4tti

5,426 posts

154 months

Thursday 10th November 2016
quotequote all
tofts said:


That gap!

unkown rebuilder.
You have all the spacers there... that follower looks odd though.

I doubt that lateral movement though has caused what your seeing. It looks more like failure of case hardening. If the follower has moved laterally presumably the shims gone and the valve hasn't been lifting properly for some time.

Regardless that engine is pretty much shagged though....

tofts

Original Poster:

411 posts

155 months

Thursday 10th November 2016
quotequote all
Im looking at the whole valve train now, and its clear that there could be problems down the road.

Just replacing the cam with a single follower is not an ideal choice, as its probably going to knock the new cam out or kill the old followers. Theres movement in the valves and thus play in the guides, which would explain the fouled plug on no5. The exhaust cam isn't looking so pretty, I'm fairly certain that the rebuild consisted of reusing as many parts as possible. Now some of those parts have nearly 70000 miles on them! Most of the measured inlet valves are very tight 2-4 thou so it suggests stretched valves or lots of valve wear, either way new valves.

It needs a head overhaul but I'm not sure its going to be within the budget of the owner at this time. Its a shame really as now I have sorted out the other bits and bobs the car is quite sound. It even ran quite well apart from an odd high pitched "tinging" I noticed. Exceedingly subtle, but noticeable if you listen to a lot of these engines.

It only came in for a quick 6k service, but after I pointed out some issues the owner asked to upgrade to a 12k. You have to wonder how much longer it would have lasted!

Jody


Edited by tofts on Thursday 10th November 12:45

m4tti

5,426 posts

154 months

Thursday 10th November 2016
quotequote all
Probably won't last too much longer as the majority of that cam lobe is cycling round the system. Presumably sanding the crank bearings back nicely.

What makes you think those valves have stretched rather than the seats worn.

I'm stunned anyone would actually want to run that any longer.



Edited by m4tti on Thursday 10th November 14:35

Andy_mr2sc

1,223 posts

175 months

Thursday 10th November 2016
quotequote all
Yes YouTube is a great resource for listening to engines....

tofts

Original Poster:

411 posts

155 months

Thursday 10th November 2016
quotequote all
m4tti said:
What makes you think those valves have stretched rather than the seats worn.
Edited by m4tti on Thursday 10th November 14:35
Rang up powers this morning just to get an idea on parts cost, happened to be Dom who answered. It was his suggestion on the stretched valves, its a very early engine, looks to have original cams etc

tofts

Original Poster:

411 posts

155 months

Thursday 10th November 2016
quotequote all
Andy_mr2sc said:
Yes YouTube is a great resource for listening to engines....
Text can come across differently to how its meant, but it does seem like your inferring I don't know how the engine should sound...



In addition to the above, I have in the other unit a 4.7 Cerb, 350i and supercharged Griffith.

Edited by tofts on Thursday 10th November 15:44

Andy_mr2sc

1,223 posts

175 months

Thursday 10th November 2016
quotequote all
tofts said:
Text can come across differently to how its meant, but it does seem like your inferring I don't know how the engine should sound...



Edited by tofts on Thursday 10th November 15:44
Don't worry it's just my usual p@@s taking sense of humour. No offence meant!




tofts

Original Poster:

411 posts

155 months

Thursday 10th November 2016
quotequote all
Ok great, so long as we can keep the facade up that I know what I'm doing everything is fine. Just catches me off guard when somebody guesses how I do things!

Andy_mr2sc

1,223 posts

175 months

Thursday 10th November 2016
quotequote all
Looking again at your first pic judging by the colour of the lobe it looks like its got rather hot.

portzi

2,296 posts

174 months

Thursday 10th November 2016
quotequote all
Andy_mr2sc said:
tofts said:
Text can come across differently to how its meant, but it does seem like your inferring I don't know how the engine should sound...



Edited by tofts on Thursday 10th November 15:44
Don't worry it's just my usual p@@s taking sense of humour. No offence meant!
You would cause a riot in church, with your comments smile, behave yourself.

m4tti

5,426 posts

154 months

Thursday 10th November 2016
quotequote all
portzi said:
You would cause a riot in church, with your comments smile, behave yourself.
You wait till the beer starts flowing portzi old son, then the comedy will flow.

portzi

2,296 posts

174 months

Thursday 10th November 2016
quotequote all
m4tti said:
portzi said:
You would cause a riot in church, with your comments smile, behave yourself.
You wait till the beer starts flowing portzi old son, then the comedy will flow.
A nice bit of Monastery Meed maybe smile. Gives a sinner a halo does meed :0

Andy_mr2sc

1,223 posts

175 months

Thursday 10th November 2016
quotequote all
I'll apologise in advance lads. I've a well earned bottle of red with my name on it waiting for me at home. In my defence it is well deserved after spending most of the day machining possibly the worst set of throttle bodies I've ever seen in my life.

Anyway back to the dodgy noises, magically growing valves, lost washers etc etc. HAha!!

m4tti

5,426 posts

154 months

Thursday 10th November 2016
quotequote all
Andy_mr2sc said:
I'll apologise in advance lads. I've a well earned bottle of red with my name on it waiting for me at home. In my defence it is well deserved after spending most of the day machining possibly the worst set of throttle bodies I've ever seen in my life.

Anyway back to the dodgy noises, magically growing valves, lost washers etc etc. HAha!!
Well I think we know what the dodgy noise is. That's a missing cam lobe Mary Berry could have spotted that one. I think we cleared up there were know washers... but the magical growing valves will be blamed on the monstrously high spring pressures I know a cheeky chap usually talks about. biglaugh

Would be fun to whip em all out and measure them.

Here's a speed six valve head I retrieved earlier. The stem is about 5mm thick so it's gonna need to get pretty hot to grow.