Noisy Tappets/bent Valve Syndrome (mi16)

[Kitch 4]

I've just done a few searches on here as I've started stripping my tappets down to overhaul them. One of them is really refusing to budge and drop the valve out, and I gather that the harder it is to remove the valve, the more gummed up it must be (and I'm assuming that makes it noiser?). Dr Sarty very kindly sent me some spares so I can probably get around it with another.

 

However, I've just been on this search and found that others have had a similar problem (a very tappet top end) which was caused by a slightly bent valve, which probably occured during their rebuild. I'm now packing my pants about this as my noise has only occured since I rebuilt the engine having suffered oil surge, but I do already have the engine out on the floor so now is a good time to start investigating even if I do have limited time.

 

The tapping didn't sound like it was all of them while it was running, more just one or two at the timing end (roughly). Unlike other tappet issues, it got worse the hotter the engine got and was normally at it's quietest having just been started cold.

The car ran fine and performed quite well. Having removed the inlet manifold already, there is no trace of carbon in the port, which I assume there would be if an inlet was slightly bent (assuming again it would be the inlet that was bent as it is so much bigger).

 

I have pictures of pretty much everything on the engine so far, and would be grateful for any advice. Ideally I'd just be able to refurb the tappets, refit them and have the problem solved, but if I have to remove the head and attend to some valves I'd rather it was now!

 

I really don't know as on one hand I've got a very badly gummed up tappet and thats only the second one I've got to (the first came apart fine) but on the other I rebuilt and re-timed the engine a couple of years ago (around 12k miles) without using timing pins! I tried to be very careful when I did time it, but I guess it's possible 2 valves might have lightly caught each other?

 

Thanks

Edited February 5, 2008 by Kitch

[pip470 61]

I new of these tapping problems especially after cambelt failures so was gutted to hear my engine tapping when it started to get hot (xu7jp4) but it turned out to be the rear timing belt cover hitting the cam pully. Might be worth a check, see if there are any marks. Phill

[Kitch 4]

Cheers Phil. Mine did this too a while ago, but has since been sorted.

I'm pretty sure the noise is either the valves, or the tappets. I just don't know if theres anyway of checking the valves without removing the head. Was thinking about measuring the height of the top of the valve in relation to the head, but I guess this could vary purely down to the make of valve or something?

[Tom Fenton 1,548]

Do a compression test, if you do have any bent valves they will not seat properly hence this will show as poor compression.

[Kitch 4]

I did think about a compression test, but the last two people who have had this didn't have a cylinder down on compression. I've already removed the cams etc to do the lifters, but theres probably no otehr way is there?

[pip470 61]

With the cams removed, a leak down test is perfect for testing for bent valves, Would be better than a compression test too. Its just having the equipment really. Phill

[Kitch 4]

What is a leak down test then?

 

Just a thought....could I pour petrol or white spirit or something down the ports and see if it drains away?

[welshpug 1,666]

leakdown is exactly what it sounds like, you remove a spark plug and pressurize the cylinder with compressed air, see how quickly the air leaks out and where.