Friday, January 09, 2009

Diesel Mechanic Information-Setting Valves Using The Rocker Method

Setting Engine Valves

Setting engine valves is the same for every diesel engine made if you use a certain method. If you rotate the engine to a particular spot lining a pointer or engaging a timing pin, that's diesel mechanic information documented by each individual manufacturer.

You rotate the engine over to TDC (top dead center) and adjust 1/2 the valves then rotate 360 degrees and adjust the other half. The DT 466 E engine pictured above has the same valve clearances when the engine is both hot or cold.

Would If You Don't Have A Manual?

There's a universal valve setting method that I use which can be implemented on every diesel engine made. It's called the rocker method which eliminates the need for a service manual when the time comes to carry out this operation.

However you do need to know the intake and exhaust valve clearances commonly found on the decal attached to the block.

Here's How It Works

While rolling over the engine watch the valves open and close. On a 6 cylinder model #1 and #6 cylinders rise and fall together from TDC (top dead center) to BDC (bottom dead center). The same goes for #2 and #5 as well as #3 and #4 cylinders.

Think of these 3 sets as sister cylinders. Every time a piston reaches TDC the stroke will either be compression stroke or and exhaust stroke.

Follow The Firing Order

The firing order on an in-line 6 cylinder engine is 1-5-3-6-2-4 I always start at #1 cylinder. While facing the engine rotate it clockwise and watch #6 cylinder for the exhaust valve closing

When the exhaust valve closes the intake will just start to open(this is why it's called the rocker method). As soon as you see the intake valve moving STOP turning the engine and adjust the Intake and Exhaust valves on #1 cylinder. #1 is now on compression stroke (both valves closed/ rockers loose) while #6 cylinder is on the exhaust stroke.

Repeat With The Next Cylinder In The Firing Order

The next cylinder in the firing order is #5. Rotate engine until #2 cylinder is on the intake /exhaust valve overlap then adjust #5 valves. The same goes for #3 cylinder (next on the firing order) #4 valves go through the overlap process and so on through #6-#2-#4 cylinder valves.

This is diesel mechanic information you can use all the time if you have an in-line diesel engine that needs a valve set and you know the valve clearances.


Anonymous said...


hi john. this is a great information.

John Whelan said...

Thanks Pedro,

This is a fail safe method to adjust valves and works for any diesel engine.

Kapil Jambhulkar said...
This comment has been removed by the author.
mk said...

shu...I'm looking for the valve clearance for a Nissan 2.5 diesel ...pls can you help with I have a tappet/valve nock.

J. E. Whelan said...

I recommend signing up with the Mitchell 1 online repair manual. You can buy a week subscription for around 12 bucks. It has everything you need to know.

Anonymous said...

Your method is great but the valves are backwards. While watching #6 cylinder you need to watch for the exhaust valve closing and the intake valve opening.

J. E. Whelan said...

Thanks for the heads up! I must have been day dreaming...I'll edit the post asap.

Diesel mechanic said...

My car suffers the problem of cold starting. I have been in a search of some good Diesel mechanic that can provide nice repairing service.Can you suggest me something.

motorcycle mechanic said...

Hi John, do you know about best motorcycle mechanic?? Tell me as soon as possible as want to hire someone on urgent basis but on cheap rates.

Richard. said...

I am having a diesel Mitsubishi Car model. I have it from last two years, nut never got any problem from it, but these days it’s getting some engine starting problem. So please suggest me a proper diesel mechanic.

diesel mechanic

Maverik said...

I have just bought a IH 4700 WITH DT466E (195hp), AT545, 478 REAR GEAR RATIO.

I want to use this for over the road work. I have always driven small vans prior, and I am concerned tht this combination of transmission will have too much rpms at highway speeds, and may not even go very fast mph. I need to drive 1200 miles to get it home, and I have not yet driven it.

I have been told that a solution could be to lower the rear gear ratio down into the 300's. I just talked to a truck mechanic who said this engine doesn't have enough HP to lower it that much, and woul only go down to a 430 rear gear ratio. Even then he is concerned that this set up is not have the HP TO KEEP THE SPEED UP AT HIGHWAY SPEEDS AND WILL LUG.

He said it would be better to switch out the trans to a manual with more gears. He said the cost would be $3000.....but he is far away, and I think where I live the cost would be much higher. The rear gear ratio change will cost $2000 here.

I have been out of work, and have little $ left after buying this truck, so I plan to find whatever work I can (not necessarily with the truck, but maybe) and save up the necesssary cash to have adequate reserves to go out on the road. Meanwhile, I wil modify the truck for over the road. The truck has a crew cab which I will turn into a sleeper.

Maybe I can get work for the truck locally, or at least not real long distance runs. Thus, while I save up money, and can get used to the truck, and make sure it is totally ready for the road. It is a beauty with only 77,000 miles on it and a 24' box.

The rpms and only 4 gears forward is what is bothering me.

I am new to running this big of a truck, as I only drove cargo vans before.

What do you say?

Yogesh Mokal said...

Very good article.It has cleared my doubt of Setting Valves Using The Rocker Method.