valve lifters/valve clearance adjustment

Bleh, I was always in and out of the valve cover on my ol' Trooper
making sure all the rocker clearances were right. But that head had
crappy valves and seats by design...
.
_H*

 

Hydraulic tappets were, I believe, originally introduced so that engines would go longer between lash adjustments. Also, they're lots quieter than solid cam followers.

They can be problematic, too, though. Not changing the crankcase oil as recommended can clog them, and they can also fail internally and collapse. They are also more prone to float, because they weigh more...and they, too, need periodic adjustment, to keep them within their range of operation.

[laughing] I used to adjust the solid lifters in the 289 powering a '65 Mustang; I still have this weird feeler gauge and a set of these little clips that would divert the oil flow spurting out of the tops of the pushrods!

The engine in my '73 Pinto (the German 2000cc unit) is single overhead cam with solid cam followers, for example...

 

General Motors Holden had hydraulic lifters in the Camira engine which were in the head and the rockers pivoted on them at one end, the valve at the other and the cam ove the top. Mitsubishi had miniture hydraulic lifters in the end of the rockers on the 2.6 litre SOHC 4 cylinder in the early Magnas.

The inverted bucket cam followers on my Camry never gave me any grief, 277,000 kilometres and never needed adjusting. Low mass cam followers are good in the Prius because the low mass combined with the low engine speed mean the valve springs don't need to be as hard so there is less friction between the cam lobe and the follower (read less fuel consumption). Inverted bucket followers also prevent side loads on the valve stems reducing wear and reducing valve stem seal leaks, lowering emissions.

 

<div class='quotetop'>QUOTE(apriusfan @ Oct 27 2007, 01:50 PM) [snapback]531029[/snapback]</div>

Mid 80s Mazdas needed tappet adjustments about every year. It's just different engine designs need different maintenance. Not every car is a Toyota.

 

<div class='quotetop'>QUOTE(patsparks @ Oct 27 2007, 06:07 AM) [snapback]531145[/snapback]</div>

Not denying that. I was just surprised to learn that the Prius' engine has solid tappets (and more to the point, adjustment is a PITA or a major league PITA).

 

<div class='quotetop'>QUOTE(apriusfan @ Oct 26 2007, 11:24 AM) [snapback]530790[/snapback]</div>

Being an LSx fan I would have to agree here. In most cases the hydraulics work just fine under 6k rpm. With a new cam, pushrods and proper re-clearancing they will rev over 6,500rpm with little problem. Some of the guys trying to for big N/A power and 7k rpm will often switch to solid roller. These seem to require more maintanence and are noisier. My 5.3L truck engine was set to shift at 6,300rpm and I would cross the beams at 6,500rpm. That being said, there are better ways to skin a cat out there. I just watched a PSCA video with Justin Humphrey's 2JZ powered Lexus run 7.0@199mph!

 

Another important thing to keep in mind is that the modern low friction OHC valve designs are almost universal. If not OHC then roller lifter with pushrods.

For emissions control the API oils rated Sl and especially SM have really cut down on an important antiwear additive that was *cruicial* to prevent early camshaft lobe wear running flat tappet lifters: ZDDP

In many cases, the antiwear additive package ZDDP is 1/2 to 1/3 the level it was when oils were rated SE and SF. For a modern motor, this shouldn't have any impact, or at most a very minor impact, on component life

Those who have older vehicles, especially an antique hotrod with fairly high valve spring pressure on flat tappet camshafts, can expect very severe camshaft lobe wear. You will have to use an oil with high levels of ZDDP. Most HD diesel oils such as 15W-40 still contain high ZDDP additives, so they will work fine in an older car

The Europeans tend to require high ZDDP levels especially for highly rated ACEA A3/B3, B4 rated oils. As an example, Mobil 1 0W-40 European Car Formula has around 50% more ZDDP than Mobil 1 5W-30.

The reason ZDDP was removed has to do with the catalytic converter. It is thought that over the extended warranty of the typical catalytic converter in the US - up to 10 years - that the phosphorous deposits might impair the catalyst

The jury is still undecided on that one. MB, BMW, etc have to meet the same extended emissions warranty in the USA, and they still require an ACEA spec motor oil with high ZDDP levels

Perhaps cost has a lot to do with it. ZDDP is a proven antiwear additive, but does add slightly to the cost of the oil

On the topic of valve adjustments: a coworker with a 2002 Honda CR-V reports that regular valve adjustments are needed or a valve may burn. They tighten in use. Fortunately the adjustment procedure is fairly easy and even a dealer will charge under $120 to do so

Otherwise I have never fiddled with valve adjustment. The 1984 Ford with 302 V8 at my hobby farm has around 527,000 km on it and I have never touched the valve adjustment. No noise and it works fine, but it was also very well maintained and run on HD diesel motor oil the entire life

A hint on those vintage Ford V8's: valve adjustment is typically performed by changing pushrods. The pushrods are in many different lengths, and it's tricky to keep track of the lengths. If for any reason you have to take the heads off, you MUST properly sort the pushrods! Same as the hydraulic valve lifters if you want things to be as worry free as possible

If you treat it like a Chevy and just throw all the pushrods into a box, be prepared for some grief when you finally get the motor assembled and running

 

Does anyone here know what all thicknesses these lifter (buckets) come in?

 

From the 2005 repair manual:​

"The lifters are available in 35 sizes in increments of 0.020 mm (0.0008 in.), from 5.060 mm (0.1992 in.) to 5.740 mm (0.2260 in.)"​

 

My old Taurus SHO (a 1990 model) uses the shim and bucket setup. I check them at every 60k tuneup but I have never had to replace any (I'm at 260k). It's too bad Ford did not get Yamaha to design the rest of the car.....

 

BULLET proof the bottom end, shot peen the rods, port and polish the heads, dual springs, roller cam with rockers, redline at 11-12K, NOS to boot.

my prius dreams this at night.............

 

My 2005 has 120000 on it and has a couple of valves clicking especially when cold. Most engines I have dealt with tend to tighten the valve clearance with age. The valve seat area is the most likely to wear resulting in the valve sitting deeper into the head and that makes the valve stem stick up further. But every engine series and each engine's wear can be a littler different. Generally a valve that is clicking has GREATER clearance which is generally not a big deal. Tighter clearance is a much bigger issue. If the clearance goes away entirely a burned valve is the result. That is a bigger PITA than a valve adjustment. CHECKING the clearance is not as big an issue as actually having to adjust the valves so I am thinking a looky see is on my next couple of months to-do list. For greater context I use my Prius on a mail route in Wisconsin and it is hard use, constant braking and acceleration to go 60 miles in 4 hours. With lots of that time off on the gravel and dirt shoulders. So far my used Prius is holding up well. I have replaced the rear brakes once and it appears that will be a 25,000 mile item. Front pads were just done so I am hoping for about 50,000 miles out of those.

 

For the record, my old 1983 Honda Nighthawk 650 motorcycle had self-adjusting hydraulic valves. Redline was around 10,000 RPM.

1983 Honda CB 650 SC Nighthawk specifications and pictures

 

gggGary, this is off-topic for the thread, you are replacing rear brake shoes at 25K intervals and not the fronts. To me this suggests that the rears are dragging and the self-adjusters are not working right. It should be pretty easy to find out whether this is a correct prediction.

 

RE: '07 recommended maint. book. I asked two service advisors at different dealers about the "engine valve inspect" line in the 60K recommended list and both were unfamiliar with it. Is our conclusion to "let it ride" (there is no typical valve lash noise) given the complexity of this adjustment?
thanks for your thoughts.

 

Often forgotten - check clearances . . . jiggle the rods after you snug up the "big end" caps.