Rod knock?

[Kuldar]

More bad luck, someone should come tomorrow to pick up the car, but when driving today it started knocking, my guess is big end bearings. It makes noise from idle upwards, it was really painful to drive it back home(5 miles), no performance issues, so that should eliminate spark plug option. Any ideas what to check. Or experiences with changing bearings, is it engine out job?

 

[stephen newberg]

This engine almost never throws rods or main bearings. Much more likely is that your cam sprockets have moved and the values are not hitting the tops of the pistons. Sorry.

pax, smn

 

[Kuldar]

This engine almost never throws rods or main bearings. Much more likely is that your cam sprockets have moved and the values are not hitting the tops of the pistons. Sorry.

pax, smn

Thanks for quick replay.
Is that worse? I don't know. As I have that gearbox issue, it's happened quite many times when driving at higher speeds 60 or more mph it shifts into 1st gear and then revs go up very quickly and it feels like oh shit, I usually manage to quickly shift to neutral, but that might have done some damage to it. The knocking sound feels like coming from top of engine, but not sure. When I've had big end bearing on other car then the knocking sound came only after 2000 rpm-s, but this one has it from start, is that a sign that's top end noise.

 

[stephen newberg]

Yes, it is worse. Its very likely at this point on at least one bank many valves are now dead as are the pistons. It is an interference design engine, so when the cams are not in the right position, the pistons and the valves hit. Up above I had a typo, it should have said 'now' rather than 'not'.

So, you are likely looking at a rebuild, and in most cases that is far more money than is worth it for a 15 or more year old car, as the parts are expensive.

To be certain, you need to pull the head covers and see if the cam sprockets are moving, but it certainly seems likely from the sounds of it.

pax, smn

 

[jimtash]

You can find a new shortblock on Ebay for right around $500. There's also a used on on there for $100.

 

[SHOZ123]

It's the head if the cam spun that they would need. The block is probably good.

I changed rod bearings on my '97 once. It was not too bad as long as you put everything back like you took it off.

 

[kevinspann]

If it ran fine, it may not be the cams...I thought you said they had been welded?

It could have blown out a plug...

 

[Kuldar]

I'll check tomorrow if rain stops and let you know. Cams are/were welded when took front cover off.
Just to mention that noise came like switched on, there wasn't any slight noise or anything else before. Oil dipstick showed bottom of the OK scale, so should been ok.
Went and bought 2000 BMW 728 today - £850, cars are cheap here.

 

[stephen newberg]

I have read of a number of cars where the front cam sprockets got welded but the backs were skipped. You will have to pull both covers to know. But Paul is right above, its going to be heads you need, if it was cams, not a block.

pax, smn

 

[whiteman_01]

I just got done building a motor due to a spud rod. It can happen.

 

[stephen newberg]

Of course it can happen. Its just not a common problem on these motors.

pax, smn

 

[Kuldar]

Update:
Today rain stopped and after lots of coffee I decided to see what's wrong with it. One of my mate listened the noise and guessed it's probably just valve and it seems to be so.
Took it all apart, nothing wrong under front cover, welds still looking good.
Rear cover was bit more challenge, one bolt broke into head(the one at the back of engine), did got it off and saw a broken valve there. All welds good as well.
So is that good news? Valve diameter is ~29mm, are intake and exhaust valves same size?

 

[SHOZ123]

What's the piston and head look like?

EDIT: Did you take that put of the top of the head? That looks like a valve shim used for adjusting the valves. It would not be the first time one's been spit out.

 

[Kuldar]

What's the piston and head look like?

EDIT: Did you take that put of the top of the head? That looks like a valve shim used for adjusting the valves. It would not be the first time one's been spit out.

Yes, it was on top of the head. I don't know about pistons or head condition as I haven't removed the head, I'm waiting for opinions what to do next.

 

[SHOZ123]

It probably just needs a new bucket for the under the shim. I would guess it came out because there was too much out of adjustment. So the rest need to be checked for clearance.

Find the valve it came off of and rotate the cam to see if the cam was damaged.

 

[Kuldar]

It probably just needs a new bucket for the under the shim. I would guess it came out because there was too much out of adjustment. So the rest need to be checked for clearance.

Find the valve it came off of and rotate the cam to see if the cam was damaged.

Thanks, as you can see I don't know much about valves or any other stuff there. What should I look to find from where it's missing. And what makes that knocking/tapping sound.
It did happened wheb box downshifted and revs went to 5000

 

[SHOZ123]

The cam lobe presses against a shim. The shim sets on top of a bucker. The bucket sits on top of the valve spring.

So one of the cam lobes has a missing shim under it.

You need some special tools to take the shims out.















Checking the clearance is done with a feeler gage.

 

[Kuldar]

Had a look and found the missing one. The bucket edges seem to be bit damaged, is that going to be a problem. Camshaft seems ok, just a little bit damage/scratch on one side. Can I just get another shim and stick it in or is it going to be more complicated. And where I can get shims for it.

 

[SHOZ123]

If the one shim got spit out it may be because it was too loose. So check the rest.

It's a bit of a procedure to to the valve adjustment. You need the special tools to get the shim out to check it's thickness.

I have buckets and some shims. But you don't know what you need for shims yet. Motorcycle shims too can be used as long as the diameter is the same.

 

[Kuldar]

If the one shim got spit out it may be because it was too loose. So check the rest.

It's a bit of a procedure to to the valve adjustment. You need the special tools to get the shim out to check it's thickness.

I have buckets and some shims. But you don't know what you need for shims yet. Motorcycle shims too can be used as long as the diameter is the same.

Thanks.
What will happen if I don't fix it and use it like it is. Or what if I just get one matching shim and stick it back in - what will then happen. The reason I'm asking is that the gearbox is knackered anyway and it has some other issues as well and I'm not planning to fix any of these, I'd rather sell it cheap/break it and buy a new(old) car. It would just be nice if it would work for 2 months.