Date: Mon, 26 May 2014 08:40:16 -0400
Reply-To: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Subject: Re: Engine Advice Needed-Valve lifters and adjusters.
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It is fairly common for both the adjusters and the valve tips to wear, sometimes in very funny patterns. I have seen the valve stems cup and wear across the back. I have seen wear to the point that the keepers fell off and the valve would go part way into the cylinder. Particularly on the AMC heads.
The air bound lifter thing holding the valves open is non sense. Air is easily compressible, it is the oil that is not. As for lifter bleeding when they remain noisey that may be due to being air bound but more likely one of the check valves is stuck. Normal operation requires that oil actually goes through the lifter through the push rod the lubricate the rocker shaft and some of that sprays onto the valve stems.
Although rare on high mileage engines noisy lifters can be caused by the valves sticking in the guides. I have seen on new engines that the clearance was not right and just after some oil (or fuel on the intakes) leaves a residue the valves will not close fast enough to keep up with the lifter motion. Letting the engine warm up expands the guide and loosens the film and lets things work normally. I have seen this on older engines with excessive deposits. This is one those things that better oils help prevent. This is the most common cause of bent push rods or push rods falling out.
As for valve adjustment with the hydraulic lifters there are some things to be considered. For one they should never be operated or adjusted to have any lash, (clearance). If the lifter is not pump up the piston in it will be worked as the valve is opened and closed. As the valve opens that piston will slam against the clip holding it in. The clip can fail and now you get the guts of the lifter dropped in the engine. Let a piece jam in the slot in the lifter bore so it jams the lifter and the engine case is now good to be melted into toy soldiers. BTDT. Do the two turns. This puts the piston near the center of its travel range and you shouldn't have to deal with them until the engine wears out or needs some other maintenance.
Another consideration is the effect on valve geometry. The angle of the rocker as it hits the valve is critical. The goal is to swipe across the back of the valve causing some rotation. With the rocker at the wrong angle excessive side load is placed on the valve causing guide wear. When heads are rebuilt this is something that needs to be considered. If the seats are cut the springs should shimmed that the stems shortened to compensate. If all the seats are cut it is common to shim out the rocker.
Dennis
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of Don Hanson
Sent: Saturday, May 24, 2014 2:26 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Engine Advice Needed
Thanks, Mark....I learned something there. It never occurred to me that
the adjusters themselves could be worn...but now that you've pointed that out, I can certainly see the possibility...no, even likelyhood...of those adjusters getting worn or bashed flatter than before in just one spot...especially on a motor that had a big angle at that junction of moving parts.
I've never heard of a WBX motor having 60psi oil pressure at warm idle...
On Sat, May 24, 2014 at 10:34 AM, mark drillock <mdrillock@cox.net> wrote:
> If it was in my driveway the test would now be to loosen the valve
> adjusters a full turn on that low reading cylinder. Then compression
> test that cyl again.
>
> At this point I would pull the 1 plug, test the compression again to
> get a new base reading and since the other plugs are still in, then
> remove valve cover, loosen 1 adjuster for that cyl exactly 360
> degrees. Test compression, loosen the other adjuster 360 degrees, test
> again. The reason for 360 degrees is that the adjusters get flat spots
> worn into them over time and a fraction of a turn loosening can
> actually bring a high spot into position and then the clearance is
> actually tighter rather than looser. Having 2 new adjustors on hand
> might be good too so you can replace the adjusters if mushroomed or pitted.
>
> Mark
>
>
>
> Loren Busch wrote:
>
>> In a '90 Westy, stock 2.1L WBX with 185k miles, auto tranny
>>
>> Recent compression test is 150, 145, 135, 70. Number one is 70.
>> So, two questions.
>> How long can I drive with this condition before I have major problems?
>> And second, what is my best solution to this.
>> BTW, oil pressure is good, 60 psi at idle warm.
>>
>>
