Engine/Transmission (1998.5 - 2002) 24 Valve Overhead Adjustment

[TAbbott]

Anyone know at what mileage this should be done? Truck has 76,000 miles on it and never been touched. Runs great, but .....

 

[John - K5AWO]

If I recall correctly, Cummins recommnends every 100,000 miles? I have seen it said at 150,000 miles. There is a good how to article compiled from TDR and other sources at CumminsDatabase.com :: B Series Valve Clearance Adjustment

Also, if you click on the FAQ link at the top of this forum, there is an article called Effects of Valve Timing

 

[SHobbs]

I do mine every 50k. Don't care what the books say about 100k or 150k. It's one the easier things to keep up with. Some notice a difference in power and noise afterwards.

 

[VicR]

This is on my to do list as soon as I pull the camper at the end of the month. What is the going rate for this job?



Thanks,



-Vic

 

[TSRAM]

I see I'm not the only one that doesn't drive theirs much huh VicR? I just tripped 82,000. Got new short block at 65k thanks to a 53 block. I guess I'll be doing my valves in a few years.

 

[Warpig]

This is on my to do list as soon as I pull the camper at the end of the month. What is the going rate for this job?



Thanks,



-Vic

Takes less that 30 min

 

[Wyomingcowboy]

If I recall correctly, Cummins recommnends every 100,000 miles? I have seen it said at 150,000 miles. There is a good how to article compiled from TDR and other sources at CumminsDatabase.com :: B Series Valve Clearance Adjustment



Also, if you click on the FAQ link at the top of this forum, there is an article called Effects of Valve Timing

this is for a 12V engine

 

[VicR]

Takes less that 30 min

Hmm. I might have to look into it a little more then. I wouldn't mind doing it myself.

I see I'm not the only one that doesn't drive theirs much huh VicR?

You got that right - I need to find more places to go! I've got a 1500 mile trip coming up this month though.



-Vic

 

[RCook]

Here's the cheatsheet I use:



ISB VALVE ADJUSTMENT



It's not difficult, especially if you've ever adjusted valves before. I've done mine several times now. I don't bother with the paint mentioned by Chad Sheets. I write down where they are when I first measure them, and where they wind up after adjusting. Checking them again after adjusting is well worth it. After the first couple of adjustments, they haven't changed very much, but it’s still worth it - takes less than an hour. I do them maybe once a year, especially before taking off on a long heavy-towing trip.



TOOLS NEEDED

Big channel lock for unscrewing the round plastic timing cover (manual transmissions)

Small mirror for viewing timing marks more easily

22mm or 7/8 socket, w long-handled ratchet, for turning engine via alternator

15mm ratchet wrench or socket, for removing valve cover

9/16 wrench (a longish box-end works well), for adjuster nuts

5 mm hex key, for adjusters

Feeler gauges



from Steve St. Laurent:

I finally was able to get around to adjusting my valves since I have 100,000 miles on the truck. Here's what I found - intake valves were from . 012-. 015 (optimum is . 010 (. 254mm) - spec is from . 006-. 015) and exhaust valves were . 021-. 024 (optimum is . 020 (. 508mm) - spec is from . 015-. 030). I was blown away that they were still within spec after 100,000 miles - and I haven't been exactly easy on the engine. I set mine slightly tight at . 008 (. 20 mm) on the intake and . 018 (. 46mm) on the exhaust. A note to anyone adjusting theirs - there is a lot of play in the Y from the camshaft to the valves on the 24v engine. I adjusted mine and then cranked the engine over and then rechecked them - it took about 6 times of adjusting them before the numbers were consistent on the next rev (I've adjusted TONS of valve trains over the years BTW). I continued to adjust them until I was able to get a consistent reading for 2 revolutions after I adjusted them.



from Chad Sheets:

Back all the adjustment nuts off on all rockers, then run them down with your fingers until they touch (you will only be able to run down the rockers with no tension on them... the ones with tension will have to wait their turn on the next round when you rotate the engine 360 degrees. Zero the gauge out and adjust for ever how many mm or whatever measurement you want to use.



1. Put cyl #1 on TDC by using the TDC mark behind the crank case breather on the front of the engine. You will have to remove the breather (if it's an automatic, or the round plastic timing cover if manual)... I believe it unscrews. You will see "TDC" stamped at 12 o'clock inside the case and a mark on the fuel pump timing gear. Put that mark on the 12 o'clock TDC position.



2. Remove the valve cover, and mark the following INTAKE valves with a paint marker, 1,2,4



3. Now mark EXHAUST valves 1,3,5 with the paint marker. You should have 6 rockers marked.



4. Adjust the INTAKE valves somewhere between . 15mm and . 38mm. I shoot for the middle of the road . 25mm.



5. Adjust the EXHAUST valves now between . 38mm and . 76mm. Again I shoot for middle of the road about . 57mm.



6. Give all the rockers a good wiggle before removing the gauge to make sure all the play is out of them.



NOW ROLL THE ENGINE OVER 360 DEGREES (180 degrees on the timing mark) AND ADJUST THE 6 ROCKERS NOT PAINTED.

 

[radyvolk]

I have a couple of questions.

Does the tolerance increase or decrease with engine wear?

Does . 002 make a difference in performance? noise?
I checked my tolerances & found the intake at . 012 & exhaust . 022 & I will adjust to . 010 intake & . 020 exhaust. I'am wondering if . 002 will make a noticeable difference.

Thanks Randy

 

[2000BlackCloud]

Rule of thumb for me is, if the valve cover comes off I'm adjusting them all. Just for peace of mind. Also if you are at . 012 & . 022, you could be . 004 out because alot of guys that eat, breathe, and sleep Cummins say to run it at . 008 & . 018. . Just my 2 cents worth. Let your conscience be your guide!

 

[DNewell]

I've got a thread running on the performance changes, but can anyone tell me what going to looser tolerances will do for performance? When I did mine, I ended up tightening them up quite a bit, basically to . 008 on intake, and to essentially . 01996 on exhaust(which is close enough to say . 02. I know that they were quite a bit looser when I did the adjustment. I bought the truck with 115k miles, and she's now got around 138k. I don't think that they had been done before. If I go looser, what can I expect in terms of performance? Will I get better top end power? I noticed that by tightening them up, I got better lower end power, and less on the top end. I'm talking about better power up at 2800-3200 rpm range. Not that I drive there all the time, and I know that it's pointless to have power in that range, but by tightening up the valves, does this help to promote better lower end power? I know you can't go too tight, because you risk burning a valve.

 

[petersonj]

The manual calls for valve adjustment at 105,000 miles. I did mine at 115,000 and all valves were within specs. I just gave it a fine tune adjustment.