The Correct way to change your TIMING BELT!

kjjet · **Posted:** Wed Jan 15, 2014 12:01 pm

With a growing number of people attempting to change there timing belt and or looking for someone to do it for them, I think its about time everyone knows the correct methods and why. Then they can choose for themselves to do it correctly or not and have the knowledge to ask how the proposed mechanic who will be doing it.

I understand what some are doing and why. I believe if you are going to advise anyone as to perform a job on an engine like setting the timing! Your information should be correct! Just becouse its on Youtube dose not mean its correct. I know lots of people have done this and their Jeeps are running good. Some even travel around the US changing belts. But done per the Wrong way leaves room for error.

The Timing system on the CRD is like several small engines with overhead cams that lock into position, permitting the cam sprockets to move during installation of the belt. These systems permit precise setting of the cams. The basis for the correct timing (precise) is setting the crank at a 90 degrees past TDC, Pinning the cams, Loosening the Cam sprockets and setting the pump timing. The service manual then calls for installing the belt at the crank, Using a VM belt holding tool (to assure the belt stays in the grove of the crank, I use a vice grip. Not to grip down on the belt, but attached to the crank with the tip of the pliers pressing against the belt so it dose not fall out of the crank grove) You then install the belt CCW over the Pump pulleys, loosened cam sprockets then the tensioner. No moving of the Crank. (even a tiny bit)
Now set the Tensioner with the sprockets still loosened. (most important) This places a uniform tension throughout the belt. Then tighten the Sprockets! Recheck the tension. This gives you the PRECISE timing setting of the cam's to the crank! Just like the VM factory did it.

Any other way you may have the timing off slightly. Will your engine run good? Sure but you may not have the best MPG and or power you could have had.

I believe this is very important to show new people how to do it correctly. Nothing is more important to the performance of your engine than being timed correctly. Ask your mechanic questions. Just because they say they have done lots of these is not a good answer.

Good Luck
KJJET

geordi · **Posted:** Wed Jan 15, 2014 1:09 pm

I don't disagree with the general methodology. I also set the tensioner with the cams unlocked, then tighten the cams down.

The most important thing is using the proper pins on the camshafts. Some people focus on the crankshaft and the use or not of the crankshaft pin. Here is the reality:

The crankshaft has a lot of rotating mass connected to it. None is spring-loaded like the cams. The flywheel has MANY large holes in it, and only 2 small holes that are nearly impossible to find. Further, the flywheel hole is open to the elements and *will* be full of filth and grit. If you have the factory pins, it will not thread in to this mess, and you will mistakenly think you do not have it in the correct place. The flywheel pin also does not have enough force to "lock" the crankshaft, similar to the cam pins not having enough force to lock the cams against the torque of loosening the bolts. This is why use of a counter-hold device is so imperative.

Meanwhile - I have heard about other people using tools or prybars of some flavor to force the belt on. This is beyond a bad idea! I do not use any side-force at all to install the belt.

I'm happy to discuss my exact procedures with anyone. If anyone wants to try it themselves while using my methods, that is fine by me - People pay for my skill and the fact that I have done over 15 of these timing jobs now. I can guarantee that there isn't a mechanic in the USA that has touched more CRD timing belts except possibly Sir Sam. ALL of the CRDs that I have worked on are still on the road today.

kjjet · **Posted:** Wed Jan 15, 2014 1:55 pm

geordi wrote:

I don't disagree with the general methodology. I also set the tensioner with the cams unlocked, then tighten the cams down.

The most important thing is using the proper pins on the camshafts. Some people focus on the crankshaft and the use or not of the crankshaft pin. Here is the reality:

Good to know. I use the alien key method on the crank. Agreed...the OEM crank pin is no good.

There are way to many people doing it wrong.

Best Regards
KJJET

mass-hole · **Posted:** Wed Jan 15, 2014 3:01 pm

Thanks for this, it is on my list so this is good to hear/see.

Brianawd · **Joined:** Wed Apr 03, 2013 12:59 pm **Posts:** 130

VW motri did a poopy job on the design of the cam timing. 1st they should have used a keyway on cams and cam gears. 2nd the cam gears should have had timing marks on them along with corresponding marking on the backing plate. Would have made things much more simple. But no, they wanted to make sure most people would. just pay to have the dealer do the job.

weeks101 · **Joined:** Mon Jul 30, 2012 3:29 pm **Posts:** 747

Brianawd wrote:

they should have used a keyway on cams and cam gears.

Not to split hairs, but the camshafts have a keyway. It's the the cam gears that don't.

Anyway, this blew my darn mind when I saw it. That and the torque values for the cam sprockets are only 80 ft. lbs.

Sometimes I have nightmares about it.

geordi · **Posted:** Wed Jan 15, 2014 4:24 pm

The "key way" on the cam is not usable as such. It is just a locator in the very end of the camshaft to show where the opposite side from the pin hole is.

The VW TDI doesn't use keyed camshaft pulleys either, because the spacing on the rubber belts is subject to change as they are made and wear.i don't like it either, but the reasoning is solid.

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flman · **Posted:** Wed Jan 15, 2014 5:23 pm

There is no timing on the pump, it is just a pump, not an injection pump used in mechanically timed diesels. I simply supplies pressure to the rail. I have used the marks a few times, but in my most recent job I did not align the marks. Jeep runs just fine.

Per the FSM:

Quote:

INSTALLATION

NOTE: There are marks on the high pressure pump gear and both camshaft gears. These ARE NOT alignment marks and should be disregarded.

jeepdan · **Posted:** Wed Jan 15, 2014 6:32 pm

flman wrote:

There is no timing on the pump, it is just a pump, not an injection pump used in mechanically timed diesels. I simply supplies pressure to the rail. I have used the marks a few times, but in my most recent job I did not align the marks. Jeep runs just fine.

Per the FSM:

Quote:

INSTALLATION

NOTE: There are marks on the high pressure pump gear and both camshaft gears. These ARE NOT alignment marks and should be disregarded.

This is an old argument, and I don't know the proper answer.
But, Why would Mopar go to the trouble of printing the procedure in the FSM for timing the high pressure pump, if it doesn't make a difference?
Anyhow, I have always done it, it's no big deal. I wouldn't want to work on some else's CRD and not do it.

flman · **Posted:** Wed Jan 15, 2014 8:09 pm

jeepdan wrote:

flman wrote:

There is no timing on the pump, it is just a pump, not an injection pump used in mechanically timed diesels. I simply supplies pressure to the rail. I have used the marks a few times, but in my most recent job I did not align the marks. Jeep runs just fine.

Per the FSM:

Quote:

INSTALLATION

NOTE: There are marks on the high pressure pump gear and both camshaft gears. These ARE NOT alignment marks and should be disregarded.

This is an old argument, and I don't know the proper answer.
But, Why would Mopar go to the trouble of printing the procedure in the FSM for timing the high pressure pump, if it doesn't make a difference?
Anyhow, I have always done it, it's no big deal. I wouldn't want to work on some else's CRD and not do it.

Did you miss? Per the FSM: ?

Explain why you think it needs to be timed? Does it have a separate line to each injector? :juggle:

Rail pressure is rail pressure.

Brianawd · **Joined:** Wed Apr 03, 2013 12:59 pm **Posts:** 130

geordi wrote:

because the spacing on the rubber belts is subject to change

Sent from my iPad using Tapatalk HD

That makes no sense.

diesel_guy86 · **Posted:** Wed Jan 15, 2014 8:19 pm

I don't know cp3 pumps inside out like I do the ol inline mechanical pumps, but I know there's 3 lobes or stages to a cp3 pump. I'm guessing this works like a 2 stage air compressor in that each stage bumps the pressure up. IF this true then you would want all 3 stages completed before an injection cycle would start to unload the rail. Not saying this is fact or true, just makes sense in my mind.

diesel_guy86 · **Posted:** Wed Jan 15, 2014 9:00 pm

I stand corrected. It appears that all 3 lobes suck and pump fuel in parallel, not series. A quick read also shows that it doesnt need to be timed to the crank or cam. http://www.dieselpowermag.com/tech/1204 ... tion_pump/

tedder · **Joined:** Thu Sep 15, 2011 7:19 pm **Posts:** 137

Wish this would have been discussed a few weeks ago when I was changing the belt on the my wife's CRD. I used the procedure that GDE has on their forum and it is not very good.

kjjet · **Posted:** Wed Jan 15, 2014 10:03 pm

There is good reason why the cam sprockets are not keyed. VW dose the same thing. IT's to let them move during belt installation, therefore giving you precise setting. Every belt is slightly different.

Also pump timing dose not effect the running of the engine. Timing it allows the pump stroke of the pump to align with injector firing therefore assuring longer life to the pump. VW dose the same thing.

KJJET

WWDiesel · **Posted:** Wed Jan 15, 2014 10:21 pm

kjjet wrote:

geordi wrote:

I don't disagree with the general methodology. I also set the tensioner with the cams unlocked, then tighten the cams down.

The most important thing is using the proper pins on the camshafts. Some people focus on the crankshaft and the use or not of the crankshaft pin. Here is the reality:

Good to know. I use the alien key method on the crank. Agreed...the OEM crank pin is no good.

There are way to many people doing it wrong.

Best Regards
KJJET

Not to disagree with anyone, but as an old mechanic that has done countless timing belts on gas burners and some SOC VW diesels, this was my first duel overhead cam diesel of this kind and yes indeed it is quite different from anything else I have ever encountered. :shock:

The only exception I will expand upon is the OEM crank pin lock. I did use the OEM cam and crank pins and the crank pin was a very positive position lock that did not allow the crank to move at all during the process. I personnaly had no trouble finding the hole and inserting it as designed. If looking for precision when timing I personally think everything needs to be completely locked in the required positions and fuel pump drive gear aligned to the OEM mark.
Now Geordi and a few others have certainly done more of these belts than anyone else around and their advice should be given credence and what they say about tensioning the cam belt and then torquing the cam bolts should certainly be followed for a good end result.
If you do not have experience in changing overhead cam motor timing belts; this certainly is not one to try and learn on as it's requirements are just too precise to leave to chance and possibly make a mistake which could be costly in terms of money and / or engine performance down the road... :2cents:

kjjet · **Posted:** Wed Jan 15, 2014 10:41 pm

wwdiesel... Thanks for the reply. Great points. The only reason I use the alien key method is ease on install. The Manual even shows using one. After you get the crank correct aligned to 90 deg past TDC and alien key at 90 degrees. The crank will not move. It takes a large wrench on the crank to move it. Also I hope everyone knows there is a mark on the crank to assure 90 degrees.

Best regards
KJJET

jeepdan · **Posted:** Thu Jan 16, 2014 12:19 am

No, I didn't miss anything.
And I can't explain why it needs to be timed.
I'm just saying that I have the two volume set of hard copies of the FSM, and it has the detailed illustrations and instructions on timing the high pressure fuel pump.

I have replaced four timing belts so far, all four CRDs had their pumps timed to the marks from the factory. That's good enough reason for me.
Using common sense, I will follow the FSM over advice from an internet forum anyday.
But hey, what do I know, I have been using Mobil1 0w40 for 148,000 miles in my CRD :jester:

geordi · **Posted:** Thu Jan 16, 2014 12:56 am

You've done 4, I've done 15+... And I always either maintain (if I don't do the water pump) or reset it to the timing mark on the inner cover.

I don't think the FSM has been right about a lot of things (lots of little errors) but this is a situation where doing this might not cure anything, but it won't hurt either.

camo · **Posted:** Thu Jan 16, 2014 1:17 am

Wonder what an "alien key" is?? is that some sort of ET phone home trick? :lol:

or was it allen key?
As of me. I have only done three TBs and I even align the marked on the water pump :BANANA:

why not? does not even take extra time...
on a side note, all three CRDs are still purrrring around.

The Correct way to change your TIMING BELT!

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