Engine/Transmission (1998.5 - 2002) A warning to all who do their own valve adjusments.

[BILLVO]

I have read numerous threads here about doing valve adjustments and have found one major mistake upon checking the facts on a lot of threads here.



NEVER EVER turn the engine by turning the alternator pully towards the passenger side of the engine or towards the coolant tank as I have read.



Take note of fan rotation



THAT IS OPPOSITE OF NORMAL ENGINE ROTATION. and you will not get an accurate adjustment. it may fall within specs of a recheck but it is not right. It would get lengthy as to why it is bad.



A better way if you do not have the engine turning tool is to use the dampner bolts to turn it. An easy indicator is to look at fan rotation to tell if you are going in the right rotation. If you must insist on using alternator take note of fan rotation. You will probably need to put tension on belt to get engine to turn in right direction or belt will just slip.



The minor problem to using alternator is you may loosen the pulley or over tighten it and ruin or strip the shaft and nut.

 

[flyairam]

Uh, just my thoughts... ...



If you have enough gear lash that turning backwards causes accuracy issues, then you've got real big problems elsewhere. Me thinks it matters not.



Randy

 

[chuckwilson]

Im with you BILLVO !!!!!!

 

[B.G. Smith]

Turning the engine with the belt is not a good idea, forward or backward. bg

 

[obert]

Yeah, TDC for valve adjustment isnt that critical, you only have to be "close". There should be enough duration on the cam to give you a good window.

Setting the timing on the other hand... . that could throw you off a bit.



edit:

just remembered, suppose you had an OHV engine with a belt drive cam, like say a Deutz, turning the crank backwards could cause catastrauphic damage.

 

[CFast]

So... how do the valves know which way the engine was spun? TDC is TDC. The valves don't have to be exactly set, you are allowed a set range. If you're off . 001" or . 002" you'll never tell it in HP, unless you're runnning REALLY high HP. I've dyno'd a lot of Series 60 Detroits before and after a tuneup and rarely have I gained HP, maybe 5 HP on a 500HP Detroit. But what do I know.

 

[timbo]

If your gears have enough backlash to throw off valve adjust you got serious problems!! My . 02

 

[PSchwering]

Not to mention that the timing pin drops into the camshaft gear - thus eliminating gear lash as a factor.....

 

[onestackdram]

my only issue is i have never been able to get a 5. 9 to turn over using the alternator. No matter how tight/lose the belt is. Regardless, turning an engine backward will not hurt it SO LONG AS you reverse your direction to eliminate the backlast in timing gears. IF anyone has timed a 12v you will note that you actually HAVE TO reverse engine direction. So my . 02$ dont adjust your valves unless your a relatively intellegent person with a fair idea how to spin a wrench. If your not, just pay the money and have a pro do it for ya.

 

[cruiser_2]

Get a barring tool to turn the engine and you won't have to be worried about it anyway. Right now Cummins has a tool set on for $55. 89 that contains a bunch of great tools for servicing our diesels, and it includes a barring tool. Used it this weekend and it works Great.



Cummins part number is 3399869

 

[mhenon]

So my . 02$ dont adjust your valves unless your a relatively intellegent person with a fair idea how to spin a wrench. If your not, just pay the money and have a pro do it for ya.

Come on onestackdram... you're going to scare people off from doing their own valves. I'm not that good of a mechanic (relative intelligence is debatable) and this was one of the easier jobs to do. I did use a wrench on the alternator but can't see the problem there.

Mike

 

[BILLVO]

Not to mention that the timing pin drops into the camshaft gear - thus eliminating gear lash as a factor.....

Your livin in 12 valve land there.



I am kind of a finicky SOB when it comes to doing it right or don't do it at all.



Yes it is true the B and C series cummins are a LITTLEforgiving in this area. But it can make the difference in an engine that purrs or and engine that rattles and ticks a bit more.



If you try and run the overhead on a lot of other diesel engines by thinking ITS CLOSE ENOUGH will have an expensive learning curve ahead of them if some will even start and run even close to smooth.



If all the nay sayers will reread my original post is clearly states it will be close and may fall within recheck specs but it is not as accurate as it could be.



My point is be careful. Here is an example of what a bad valve adjust can cause. The mine where I work just trashed a 3512 cat engine due to 1 valve being about . 015 loose. when the valve adjust was done someone forgot to tighten the locknut fully. the cross head came off and got caught on the high spot not in the pocket . that was enough for piston contact. on an engine that big you can't hear that because the engine is in the back of the machine. "On a kress coal hauler"It destroyed the piston which caused a chain reaction and broke the rod which broke its mating journal rod which swung around thus destroying the block. There were bowling ball sized holes out both sides of the block.



New engine to replace the destroyed one $250K



Accuracy while doing a valvetrain adjustment. PRICELESS



Anyone who has worked on larger cummins engines should understand what it takes to be accurate.



If you only like to be "close" good luck to you. It will probably catch up to you in the future.



This thread is to let anybody who has or will want to do it right know that there is a right way of doing it, It is not meant to be an arguing ground.



Especially if you did it on a someones elses engine and something "CLOSE" went wrong. would probably save a big headache.



By the way it is not uncommon for high milage engines to develop excessive gear train lash. Which can and does affect the accuracy. They can will and do run with no problems they might be a bit noisier than normal in front.



This is not my . 02 it is 20 years of diesel tech experience. and what I have seen go bad in past.



Bill

 

[Gary - K7GLD]

Bill's right on - and if all I wanted, or was willing to accept is a valve adjustment that's "close enough", I'd just leave it where it is! But the REAL mechanics are well aware that there IS a right way to do the job for maximum accuracy, and I'd sure want to either have one of them do the job, or at least follow their directions on HOW to do it properly.



We're dealing in thousandths of an inch here, and gear lash and cam ramp angle/position WILL make a difference, especially as an engine wears...

 

[CFast]

BILLVO, you're comparing apples to oranges aren't you? You say the valve was too loose, but you also say the locknut was left loose. Well yes, if you leave the locknut loose you run the risk of dropping a valve and destroying the engine. If the nut had been tightened do you think the . 015" would have caused the damage? If it's too loose it won't touch the piston, it just won't open enough, and will probably clatter like mad. But, it is a Scaterpillar and I'm a Deadtroit guy, so what do I know. I've been a diesel mechanic for 6 years now, not 20, but one thing I know is: series 60's always have loose exhaust valves and tight intake valves, and the run like that for a long time.

 

[JasonCzerak]

finding TDC

I did my valves once, tighten them down a bit, went back 5,000 miles later and they were all were I left them. I kinda guesses at TCD.



As far as TDC on a 3rd gen, there's just to much crap in the way. and from what I understood TCD is well, 12 o'clock and not like a gasser were you have the 0 degree mark off to the side (for use with a timing light).



So what I did was make a mark 180 from TDC that (BDC). it's much easier to find a mark 180 degree from TDC and line it up on the bottom



Anyone have any more accurate tricks?



Other then that, yeah, adjusting the valves are easy. Pain in the knees, especially #5 and #6.



As far as tightness with the feeler gauge, do you guys make it so the gauge is tight and can't be easily pulled out from between the rocker and valve? or just a tiny bit a play so that there is no vertical movement, or no ability to slip in a . 001 guage ontop of the . 010 intake size.

 

[JoshPeters]

OK 3 points.



On a gear driven engine, you are talking about how accurate or inaccurate things are by setting your lash and people are saying you have more issues. No you don't. You have MULITPLE gears that not only are set and designed to run in one direction, but they are helical cut(as I recall). One way they walk towards eachother. The way they are supposed to. Backwards and they push away now making the tollerances larger. Why is it that Piers said that you can be off by 4 degrees setting timing on a 12v by gear lash alone!?



If the guy left the lock nut off you can't say it was . 015 out of spec or in spec. Things walked loose at that point. It's all null and void. There is no way to check that spec anymore.



I believe there is alot to be said for accuracy while working on these engines as well. What people don't realize is this is an interferance engine. Things being just slightly off can be catastrophic. Perfect example, the machine shop where I had my head machined said they only took off . 006. They gave me an average. I believe they took . 008-. 009 off the number one cylinder area. Why do I say that? Because while I don't see any REAL damage, I have a perfect trace of number 1 exhaust valve. Will that valve be replaced when I put it back together? HECK YES! It looks fine, no bend. Will I take that chance? No.



JP

 

[BILLVO]

BILLVO, you're comparing apples to oranges aren't you? You say the valve was too loose, but you also say the locknut was left loose. Well yes, if you leave the locknut loose you run the risk of dropping a valve and destroying the engine. If the nut had been tightened do you think the . 015" would have caused the damage? If it's too loose it won't touch the piston, it just won't open enough, and will probably clatter like mad. But, it is a Scaterpillar and I'm a Deadtroit guy, so what do I know. I've been a diesel mechanic for 6 years now, not 20, but one thing I know is: series 60's always have loose exhaust valves and tight intake valves, and the run like that for a long time.

Go back and reread my post. I think you missed the details



It says the looseness caused the brigde to come out of the socket and ride on the egde of it causing the valve to move down much farther causing piston and valve contact. It also said it was an example.





Jason C it is personal preference as to the feel of how tight you set it. I perfer a slight drag on the feeler gauge I like a tighter set. That is an on going arguement for 40 years in the industry. That is why there is a recheck varience. I like a quieter engine so I like the tighter set. Most would not notice the light clatter of a looser set.

 

[RAndrae]

valve adj

Done valve adj on several CTD's never had a prob done it with the alt bolt and with barring tool never had an issue, also done many BBC and Hemi big dollar motors. Turned em forward back ward never had a prob. I guess I just payed attention to detail... ...

 

[CFast]

Well one way to settle this is for someone to do a tune up one way, set it, then bar it over the other way and check it.

Do you guys do each one at a time or set #1 on TDC or #6 on TDC. ?

 

[JoshPeters]

CFast:



Both. You have to set the engine to TDC number 1 and TDC number 6 to set them correctly on a Cummins.



JP