Valve lash/clearance

Mike Ondra

Since this seems to be a hot topic, I checked in the Volvo TMD22 manual and this is what I found under Technical data:

Valve clearance, adjustment cold engine: Inlet 0.20-0.40mm : Outlet 0.30-0.50mm

Valve clearance, check cold engine: Inlet 0.25-0.35mm : Outlet 0.35-0.45mm

What is the meaning of the 2 sets of data, and does this imply that there is an acceptable range of values rather than a specific value?

Mike Ondra


Rock Hall, MD

From: []
Sent: Wednesday, June 29, 2016 7:43 AM
Subject: Re: [Amel Yacht Owners] Diesel fuel problems and additives

Thanks, Craig, I believe that you are absolutely 100% correct.

Opinion: The consequences of out-of-adjustment "valve lash" are numerous, but the most common reason for diesel smudge on the side of the boat (which is what the original question was) is out of spec valve lash adjustment.

If I remember correctly, our 100hp and our Onan specs are around 1000 hours for adjustment.

Opinion: Regardless, I use 1000 hours on each of them. Unlike you, I believe that I have made very minor adjustments to the valve lash on at least one cylinder each time I have checked. I always do a complete check two times and a good mechanic will do the same.

Different engines have different characteristics.

Bill Rouse
BeBe Amel 53 #387
Sent from my tablet
+1832-380-4970 USA Voice Mail

On Jun 29, 2016 7:25 AM, " [amelyachtowners]" <> wrote:


To add just a bit to Bill's reply, and not to be too picky, "valve lash" is not the adjustment, it is the actual gap between the rocker arm and the tip of the valve stem. Adjusting that distance if it is out of spec is a simple process and you'll adjust both the intake and exhaust valves. The effects of being out of spec are varied, and do not necessarily cause exhaust smoke, That is, don't think that the only sign of valve clearance being out of spec is smoking exhaust. That being said, this is not something to obsess about - I check mine every one or two thousand hours and they are always in spec. I'm sure the "book" recommends more often but that's to keeps the mechanics in business.

Cheers, Craig SN#68

---In, <yahoogroups@...> wrote :


The following is my opin ion(s) and some facts:

Fact: Valve lash is the adjustment made to the intake and exhaust valves on your diesel engines to ensure that the valves open and close correctly.
Opinion: The valve lash should be adjusted on your enginenand generator about every 1000 - 1200 hours of operation. Incorrect valve adjustment (lash) will cause unburnt fuel to enter the exhaust, causing some smoking and leave a diesel stain on your hull.

Fact: Regarding your Racor filters, the filter material will deteriorate with time.
Opinion: I change Racor filters at 400 combined hours, or 1 year, which ever comes first. I think you should change those 5 year filter elements.

Opinion: When buying fuel, I like to pick a very active fuel dock. I always run the first 20-40 liters through a fuel filter/water separator funnel. If it is clean with no water, then I put the fuel directly into the tank. I have had only one occasion when I told the fuel dock to forget about it, and paid for only the 30 or so liters.

Bill Rouse
BeBe Amel 53 #387
Sent from my tablet
+1832-380-4970 <tel:%2B1832-380-4970> USA Voice Mail

On Jun 28, 2016 11:10 PM, "Kent Robertson karkauai@... [amelyachtowners]" <> wrote:

Am I the only one here who's never heard of a valve lash? What the heck is it? Where is it? How is it adjusted?




Hi Mike,
Noa has a Yamar engine which is serviced different, but we had a Volvo TMD22 on our previous boat. The camshaft cover on the TMD serves as the upper part of the camshaft bearing. When you disassemble it to check the valve clearence, you will either need a special tool (three camshaft moutings which hold down the camshaft) made by Volvo or you find a machine shop/build them by yourself.
In case the clearance is outside the tolerance 0,2-0,4 inlet or 0,3-0,5 outlet, you need to readjust to 0,25-0,35 inlet and 0,35-0,45 outlet. If the clearence is inbetween the first tolerance, you donĀ“t need to readjust.

Kind regards,
Walter (Noa, SM2K #436)