Hydraulic tappets - I need to go back to square one!

Post by **Globbits** » 06 Aug 2008, 09:21

Sorry for the heavy-duty first post. I know you should never adjust hydraulic tappets, but I did and I'm not sure how to go back now

My DG engine's tappets are all over the shop. They're not noisy, but torque has dropped off massively and she'll barely accelerate at all on lpg. So I'm assuming they're not opening enough, but bearing in mind how many times they've been "checked" now, they could be all over the shop! My excuse is that it turns out my replacement engine had been set up with:

The wrong dizzy for the engine, so timing was well off
The wrong vacuum unit on the wrong dizzy, so the engine was massively advanced
A dying carb, which has now been given a new lease of life

I made the mistake of clutching at straws whilst debugging that little lot and have badly tweaked the tappets. So I think the safest thing to do is set them all from scratch - as in get the oil out of them, then set the preload again, then bleed the blighters

Problem is, how do I get the oil out of them?! I assume I need to drain the sump, but is it as simple as running the engine 'til it's hot, draining the oil out, then waiting a day? Or are there clever ways I really should know about?

Please, any help you can give will be gratefully received

Richard[/list]

Post by **lloyd** » 06 Aug 2008, 10:38

try wiki and search for lifter

Post by **Globbits** » 06 Aug 2008, 11:18

Blimey - considering hydraulic valves are fitted on a bzillion modern cars, it still amazes me how there still isn't a consistent "this is how it's done"

Thanks very much for that, 1.5 turns after they've bled it is then! I've got a friendly garage with a compression tester, so will have words with them once I'm done

Much appreciated!

Richard

Post by **1664** » 06 Aug 2008, 12:15

lloyd wrote:try wiki and search for lifter

Post by **lloyd** » 06 Aug 2008, 12:34

1664 wrote:
lloyd wrote:try wiki and search for lifter

Hey! He found the info he needed didn't he?

I remembered seeing it there, but didn't remember the link or what it said, so was best I could do at the moment.

How you doing these days? Haven't seen you sense Bashtie. You missed a great show/contest in the wee hours of Sunday morning at Apps.

Most I've laughed in years.

Post by **1664** » 06 Aug 2008, 12:47

Yes, I realise I missed a goodun but I stayed at home thinking I might do some on the van (yeah right

) and had a birthday do saturday night too. Hope you are all well

Post by **Globbits** » 06 Aug 2008, 12:56

Hmm - well that didn't work!!!!

I ran the engine for 10 minutes to warm it up and (if any weren't already filled) completely fill the lifters. I then loosened all the lifters off (in firing order, according to dizzy position, obviously

) and they were all just touching. I backed them off again just to make sure, then back in and past "just touching". As I wound them in, the valve springs were beginning to compress, so I called it quits after 1 turn on each.

When I started the engine, it wasn't achieving compression on one cylinder for a few strokes, but then calmed down and idled roughly, but ok. Left it for 5 mins, then took it for a run. Now, it won't run on lpg at all and can barely make it up a gentle hill on petrol!!!

But to be fair, I rather expected this. My guess is that all the lifters are close to their fully-compressed state and so can't adjust outwards any more. What I want to do is basically get them back to their fully-unloaded state, so that I can then do the 1.5-turn preload thing

The wiki was useful, but doesn't actually say anything about draining them down - everything's about adjusting them up

Any thoughts? I'm happy to do an oil and filter change - it's almost due anyway - but I want to make sure that all the lifters empty out as part of the process!

Thanks in advance!

Richard (and Myrtle T Bus)

Post by **Mr Bean** » 06 Aug 2008, 17:16

Globbits wrote:Hmm - well that didn't work!!!!
The wiki was useful, but doesn't actually say anything about draining them down - everything's about adjusting them up
Any thoughts? I'm happy to do an oil and filter change - it's almost due anyway - but I want to make sure that all the lifters empty out as part of the process!

Thanks in advance!

Richard (and Myrtle T Bus)

Funny thing is I didnt know/realise they were adjustable in the first place so you have me wondering why I never met that job when I changed my heads. Anyway I am surprised that you feel it necessary to change the oil in the tappets as in my understanding there will be a gradual migration of oil throught them in the normal running of the engine and the percentage if oil in the tappets is miniscule in comparison to the whole system as far as dilution is concerned. Are you being pedantic or am I being sloppy?

Cheers
Ken

Website · Post by **syncrosimon** » 06 Aug 2008, 18:40

I think what you might be thinking of can only be achieved by taking the lifters out, and bleeding, filling them on the bench. This envolves a great deal more than changing the oil.

If they are not clacking then they should be working.

Is there something else that is wrong with the engine??

what got you onto thinking along the tappets line??

Post by **Ziegel** » 06 Aug 2008, 19:55

Best info I've seen is here:

http://www.ratwell.com/technical/HydraulicLifters.html

Post by **Globbits** » 07 Aug 2008, 08:52

Well the basic problem is a lack of power, but it seemed to be related to the valves. I know hydraulic lifters are self-adjusting, but they have limits on the amount they can move as they bottom out eventually. My thought was that, by my mistaken tweaking in the first place, I'd managed to bottom out a lifter or two. But to be honest, it doesn't seem like that's where I am

I think the best thing I can do is go back to where I was before yesterday lunchtime by untensioning the lifters (and probably leaving a tiny gap to allow them to slacken off) and letting the thing calm down!

Thanks for the pointers guys

Richard