Valve Lash Mercruiser 165

[Midnight Thunder]

Thank you to all for assistance with the lower end rebuild.

Re: Mercruiser 165 inline 6

I'm having problems with the valve lash. The orig problem was knocking in the lower end - fixed with machined crank and bearings all around.

I idle the motor at 500rpm to avoid oil spray and while warm and running adjust the rocker arm bolts till they stop clicking and then 1/4 turn. I have also tried the cold not running method as well.

Problem is, when I rev the engine up - she starts clicking. For sure it's coming from the top end. I adjusted each rocker arm by 1/4 additional turn - seemed to quieten her down but still at higher rpm and especially when she's running at full temperature, it really starts clicking.

I don't want to overtigten the rockers for obvious reasons and am worried about possibly a failed lifter or two??

Does the warm/running method need to be done at higher RPM?

Your advice and thoughts are appreciated.

 

[Don S]

Re: Valve Lash Mercruiser 165

It's supposed to be 3/4 to 1 full turn after 0 lash, not 1/4

 

[Midnight Thunder]

Re: Valve Lash Mercruiser 165

ugh... I don't have my manual here at home - it's on the boat - could have sworn it said 1/4 turn.

Does this need to be done at higher rpm or am I ok doing this at 500 rpm to avoid the mess?

 

[Haut Medoc]

Re: Valve Lash Mercruiser 165

Doing it at idle is fine, though 500 sounds a little low, but that should not affect the adjustment....

 

[Midnight Thunder]

Re: Valve Lash Mercruiser 165

Much appreciated - I will re-do it and add 3/4 turn.

 

[dirtyoldman]

Re: Valve Lash Mercruiser 165

The idle spec for this engine per the manual is 500-600, then later it says to set at 475. Mine was at 450, so I raised it to 600 before I looked it up, and now I have a hard time going into the dock, it's too fast.

 

[Buttanic]

Re: Valve Lash Mercruiser 165

If it is not quite at 1/4 turn I don't think 3/4 will be either, you may have some bad lifters. I use the 1/4 turn all the time, it helps prevent lifter pump up at high rpm which can contribute to valve float. On my racing engines I would use a .003 feeler gauge to set hydralic lifters.

 

[Midnight Thunder]

Re: Valve Lash Mercruiser 165

I will double check the manual - thinking back - I think it was a 1/4 turn for the cold method and 3/4 turn for the warm method. I will double check for sure.

If at higher rpm I still get the 'tick tick tick' - would this indicate a bad lifter? When I had them out, I was unable to depress them with my finger which I thought was the 'rough check'.

What's my next step if I still have the same problem? I'm not sure how much lifters are.

 

[Don S]

Re: Valve Lash Mercruiser 165

I just looked at Merc manual #1 and it said to turn it down 1/4 turn.
Now, if you failed to read that step further, you stopped to early. It says to turn it down 1/4 turn then wait for 10 seconds, do an additional 1/4 turn and wait for 10 seconds, then the last 1/4 turn.

 

[Midnight Thunder]

Re: Valve Lash Mercruiser 165

Very good - thank you indeed. That's where the 1/4 and 3/4 comes in. I'll give her a go as soon as the weather here clears.

And if she still ticks at the higher rpm?

 

[Midnight Thunder]

Re: Valve Lash Mercruiser 165

ok... I made sure to watch how far I backed off before the rockers started to clack - it was a full turn on each - so I guess I did get the 3/4 turn before - sorry for forgetting.

So... I took her out and under load or not -- I'm getting ticking. I'm at a loss on this one. I had the lower end re-built. What could be causing this? Where do I best start? Could failing valve lifters cause this kind of noise? It does get louder under load.

Thanks in advance

 

[ziggy]

Re: Valve Lash Mercruiser 165

w/o copying from service manual #2, locating noisy lifter,
use a round abouts 4' of garden hose. place hose near the end of ea. ex. and intake valve and listen to the other end of the hose. the sound can be localized this way to help find the offending lifter. or, another method would be to place a finger on the face of the valve spring retainer. if the lifter is failing a distinct shock can be felt when the valve returns to it seat. general types of lifter noise are hard rapping noise, moderate rapping noise which could be caused by improper adjustment. general noise throughout valve train usually caused by insufficient oil supply or improper valve adj. and intermitant clicking. in most cases where noise exists in one or more lifters. all lifters should be disassembled and cleaned and inspected as if one lifter is failing, the others will follow shortly. thats generally what the service manual says w/o copyin verbatum.
ya did keep the lifters and pushrods in order and put them back where they came from i assume.......

I just looked at Merc manual #1 and it said to turn it down 1/4 turn.
Now, if you failed to read that step further, you stopped to early. It says to turn it down 1/4 turn then wait for 10 seconds, do an additional 1/4 turn and wait for 10 seconds, then the last 1/4 turn.

that is correct. i'll add that this is done at idle speed w/ engine warm. with engine running back off valve rocker arm nut untill the vavle rocker arm start to clatter, then slowly turn down rocker arm nut untill clatter stops. this is zero lash. then do yer 1/4 turn at a time, pauseing 10 sec. untill engine runs smoothly and repeat till 3/4 turns is reached. this must be done slowly to prevent possible interferance between inlet valve head and the top of the piston which may result in internal damage and or a bent pushrod.

 

[Midnight Thunder]

Re: Valve Lash Mercruiser 165

I'm going to do exactly that. I'm also going to pull a plug (please make sure I have this right) one at a time while she is running and see if there is a major noise difference which I believe will indicate a lower end problem (if the noise changes) and if not, then I am looking at a valve train problem. I'll be using a rag and a glove to insulate myself - is that sufficient?

I thank you for your help and I will let you know how this goes on the weekend. Any other 'checks' I can perform while I am at it?

My understanding for checking valve lifters is if you can press down with your finger - she's failed. Is there a way to check this withought having to pull them? Ie. a clearance check on the rockers?

 

[Midnight Thunder]

Re: Valve Lash Mercruiser 165

Ughh...

I isolated the noise to cylinder 1 by pulling plugs. Before pulling the head - I pulled each lifter to check them just to be sure - they seemed fine - rods and rockers no sign of wear.

I pulled the head (bye bye head gasket) and found some slop in cylinder 1. I just had the crank and rods machined with new oversized bearings - we checked tolerances with plasti gauge on each rod going in - all was dead on. Cylinder 1 is the one that had the major failure (spun bearing) before. To ensure everything was 100% - I had them all machined down. I checked cylinder 1 twice because that was the bad one - was dead on going in.

All other cylinders are solid.

Time did not allow me to pull the motor - will do so today. I'm wondering if I find a problem in the rod on the crank - then what the heck after having it machined! If plastigauge shows dead on - how could this happen? I had good oil pressure + used lots of assembly lube. I find it ironic the same cylinder is showing failure. It might be a wrist pin - but if not, should I be after the machine shop to take some responsability?