Engine/Transmission (1994 - 1998) Valve Adjustment

[CBlack]

How can you tell if you need your valves adjusted?



I bought my truck when it had 84,000 miles on it. It now has 118,000+.



I remember reading when it hits 100k it should be adjusted, but some people say that it doesn't matter.



I ask because there is finally a reputable diesel shop near by that specializes in Cummins engines and particular 12V models and will adjust them for $200.

 

[Bob4x4]

Cummins recomends the 12valve be adjusted every 24k,that should help you decide

 

[LVJUNIOR]

12valves are very easy to adjust the valves on. Do it yourself and save the money. No professional shop should need more than an hours labor to adjust the valves

 

[CBlack]

Cummins recomends the 12valve be adjusted every 24k,that should help you decide

Didn't realize that one... thanks.

12valves are very easy to adjust the valves on. Do it yourself and save the money. No professional shop should need more than an hours labor to adjust the valves

I've thought about that. The guy was going to bump my timing up a bit as well while doing the valves.



What tool(s) do I need for the valve adjustment?

 

[JMcCoy]

An engine baring tool makes life a lot easier. I have an old flywheel turner that works ok. I could never get the alternator pully trick to work. The pully just slips. A good feeler gauge (not expensive). Basic hand tools. I can't remember the wrench sizes needed. don't worry about the valve cover gaskets. They are rubber and reuseable. If you end up with a bad one, (never had it happed) replace it then. There is an excellent write up in one of the TDR magazines. Step by step instructions with pictures. It made the job simple as can be. My old magazines are in storage but it was at least 7 years age. Maybe someone here can advise. The first time will take you about 2 hours, then 45 after that.



Though the book advises otherwise, you should not need to adjust your valves for at least 50,000 miles. Every time I have adjusted the valves, thay have been right on the money. Maybe others have had different experiences. Hope this helps.

 

[JGheen]

I've thought about that. The guy was going to bump my timing up a bit as well while doing the valves.

... ... and what reasoning behind adjusting your timing did he give you? I would be kinda curious about why and what setting he wanted to set them at.



Joe

 

[JGheen]

I could never get the alternator pully trick to work. The pully just slips.

Try turning the alternator pulley the opposite way. I promise it won't slip, it slips one way and not the other, I had that issue till I flipped the switch on the rachet I was using to turn the pulley.



Joe

 

[surfbeetle]

Just adjust them once a year whether you think you need it or not, I usually do around 12,000 miles a year. The mileage given by Cummins is just a recommendation. If you tow and get it too hot, you can adversely effect the adjustment and need it sooner. I was used to adjusting the valves on my VW every 3,000 miles so the Dodge is a piece of cake.

 

[fest3er]

... ... and what reasoning behind adjusting your timing did he give you? I would be kinda curious about why and what setting he wanted to set them at.



Joe

Not to mention "bump the timing while adjusting the valves"? I hope he meant "adjust the valves while bumping the timing". Adjusting the valves might take a half hour; the average Joe can do it. Not to imply you're average, JG, you know. Changing the pump timing is much more involved.

 

[CBlack]

... ... and what reasoning behind adjusting your timing did he give you? I would be kinda curious about why and what setting he wanted to set them at.



Joe

I wanted to bump the timing to 15. 5. I do a lot of unloaded highway miles and keep the RPMs at about 1800 or so and from what I've read 15. 5 would be ideal for my situation.

Just adjust them once a year whether you think you need it or not, I usually do around 12,000 miles a year. The mileage given by Cummins is just a recommendation. If you tow and get it too hot, you can adversely effect the adjustment and need it sooner. I was used to adjusting the valves on my VW every 3,000 miles so the Dodge is a piece of cake.

I've thought about adjusting them myself... if it is truly worthwhile to do it every year then I will.



I was going to pay someone as I thought it was only really necessary to adjust them once as quite a few people have mentioned that they've only done it once.

 

[GAmes]

I just checked mine today. I normally do it every 50k but somehow missed a cycle and went 95k. Three valves needed about 1/16 inch of a turn and one had to be loosened a tad. I'm changing my schedule to 100k:-laf You need a . 010 and . 020 feeler gauge, 14mm box end, and a stubby flat blade screwdriver to check and adjust the clearances. I think the bolts holding the valve covers on are 15mm. Do the check when the engine is cold. If you haven't cleaned your engine lately do it first to keep dirt and grit from falling in.

 

[Vaughn MacKenzie]

I've always suggested check the clearance sooner rather than later, but once set the lash shouldn't need checked again for at least 50-100k miles.

 

[CBlack]

What is an engine baring tool?

Went to Carquest and they had no idea.

 

[snappy]

A baring tool is used to turn the engine over. Pull the plastic plug out of the bell housing, insert tool and use a ratchet to turn engine over. The splines on the tool engage the flywheel. I know that Snap-On and Miller has 'em. Not sure who else.

 

[CBlack]

A baring tool is used to turn the engine over. Pull the plastic plug out of the bell housing, insert tool and use a ratchet to turn engine over. The splines on the tool engage the flywheel. I know that Snap-On and Miller has 'em. Not sure who else.

Thanks!



I started looking around and Geno's has them as well.

 

[Vaughn MacKenzie]

I've always gotten along fine without a barring tool, you can easily turn the motor with a socket on the alternator pulley. If you want to go forward use a socket on the crank damper.



The engine doesn't have to be spot-on top dead center when adjusting valves, just needs to be within 10-15 degrees or so.

 

[fest3er]

I've always gotten along fine without a barring tool, you can easily turn the motor with a socket on the alternator pulley. If you want to go forward use a socket on the crank damper.



The engine doesn't have to be spot-on top dead center when adjusting valves, just needs to be within 10-15 degrees or so.

To expound a little, as long as the rocker arm on the valve you are adjusting is loose, you are close enough to TDC. Besides, you can see when the valves stop moving.



Set TDC on cylinder #1 (both rockers 'loose'). Adjust all the valves that are 'loose'. Turn the engine 180 degrees. Adjust the rest of the valves. And be sure to keep track of which you adjusted, in case one or two are never 'loose'.

 

[JMcCoy]

Try turning the alternator pulley the opposite way. I promise it won't slip, it slips one way and not the other, I had that issue till I flipped the switch on the rachet I was using to turn the pulley.



Joe

Thanx. I'll try it next time.

 

[Cummins12V98]

Set the valves to 8 and 18, it will give a little better performance and is a safe setting.

Ron

 

[CBlack]

Is there a detailed diagram on where on the bellhousing to insert the barring tool?

Or which 15mm bolt to use to turn the engine over on the harmonic balancer.