Timing set replacement questions

I'm about to tear further into my 6.5 than I've ever previously done. I will be replacing the water pump with a new flowkooler model from Leroy Diesel and also putting on a fluidampr. Since my engine has almost 200k on it now, I figured I might as well replace the timing set while I'm doing the rest, and then hopefully never have to go back in there.

I have dug through these forums reading all the threads I could find about timing set replacement, IP, and how to set the timing, and I think I have a good idea of how to do it. I just want to be sure I understand how the IP part works when replacing the timing set without replacing the IP.

Does the IP (and therefore intake manifold) have to come off entirely in order to replace the timing set? Or can it just be unbolted from the front cover? Are these the same 3 bolts that allow for adjustment of the pump position? Finally, if leaving the pump in place, does that mean I need a special bent wrench or some other special tool in order to R&R those bolts?

Here's a full list of what I'll be doing over the next couple of weeks:

• new Leroy Diesel Flowkooler water pump
• new 21" fan & fan clutch (part of kit from Leroy)
• new aluminum balancer pully (also from Leroy)
• Fluidampr harmonic balancer
• new crankshaft position sensor
• new timing set (cloyes)
• new Champion aluminum radiator
• new 195° ACDelco thermostat
• new radiator hoses

I love my Suburban (nicknamed The Hulk) it's my family's camping & adventure vehicle. I've had one or two times when it was struggling to keep cool driving over some of the steeper sierra passes in the summertime heat, and want to see if I can prevent that from being a problem in the future.

Merry Christmas, and thanks in advance for any help or advice.

Wade

Welcome aboard!

No, the IP doesn't have to be removed or adjusted in any way while replacing up to only the timing set. In fact, it's better to leave it bolted securely in place throughout the job. If at any time you need to loosen, remove or adjust the IP, for whatever reason, be sure to note the witness marks on the IP and timing cover (or create a pair if there are none or only one), and align them upon assembly. The electronic pumps will compensate for any slight variation in the alignment, in any case, with an exception being those who have pushed the TDCO optimization (if you don't know what that is, don't worry about it, and research that separately if interested). Mechanical pump alignment is a simple matter of realigning the witness marks. The IP is secured to the timing cover by the 3 bolts, which also serve as the adjustment fasteners. I've never had a need for a "special" wrench, although they may make the chore more simple. I've always used whatever 15mm combo wrench that was handy. Perhaps the box angle may make a difference, or I just got lucky (I usually don't have much luck, in anything, unless you count bad luck). In any case, unless you need to go further than you've listed, it's not something you need to worry about. The only bolts you need to mess with secure the gear/sprocket to the cam, and the IP gear. Just replace them the same as you've removed them, and mind the dowel pin. They only fit one way, and if any bolt-holes go missing, it isn't correct.

The timing sets in the 6.2 and 6.5's are rather robust and durable. Before you loosen the bolts on the sprockets, measure the chain deflection, and compare it to the new set once installed. I think you'll find very little difference, if any. Also, unless you notice some damage or unusual wear on the sprockets (very rare), they seldom need replacement. Roller chains wear very differently than wafer-chains and cog-gears common on many other similar V8 engines. I've never seen this, but heard of it, usually 3rd hand (questionable authenticity, IMO). The sprocket sets aren't (very) expensive, and often get replaced as a matter of course. Unnecessary in most cases. The original factory parts are very often far superior to any aftermarket replacement, and work-hardened, worn-in parts tend to not break if they haven't already. If it ain't broke, don't fix it, IMO.

"new aluminum balancer pully (also from Leroy)" Just my .02, but you might want to do some research on the billet aluminum crank pulley. Not from personal experience, but I remember seeing several posts on other 6.5 GM diesel forums regarding it. That it caused noisy serpentine belt vibration due to no damping from the diesel crankshaft firing impulse, which is worse than a gasser. GM made that a dampened pulley for a reason. I believe GM has engineers that are much better educated and skilled than Leroy diesel.

X2^^^ on the billet aluminum crank pulley....sounds like a great idea, but, not so much....

Thanks for all the info. I have actually already completed all the work listed above after I figured out those last few questions, before my post was approved. It all went pretty smoothly. With the A/C out of the way I was able to reach all the IP nuts without any special tools. Worst part was cleaning everything off, it took me half a day just to clean the gunk off everything.

I already had the timing set from Cloyes, seemed like high quality gears so I replaced the gears and chain while I was in there. Probably unnecessary to replace the gears as mentioned, but they looked like very nice gears so figured a brand new set would be good. The new chain was actually much, much tighter than the old one. The old one had quite a bit of play, though I know from reading these forums that it's normal for it to seem pretty loose. Anyway the new one was noticeably much tighter.

I did do some research on my own about the crank pulley, both here and around other sites. It seems crank pulleys in general that have a rubber damper part don't really do a whole lot anyway from what I've read. What little rubber is in there wears out pretty quickly in terms of elasticity. The OEM one has very little rubber in it to begin with as far as I can tell. I figured with the fluidampr on there, the pulley won't be doing much damper-wise, and this way I will never have to replace the crank pulley again. The old one was in pretty bad shape. I figure worst case scenario, if it seems noisier and/or the belt life is severely shortened, I will replace it with an OEM version. Replacing only the crank pulley is pretty quick. It was just appealing to have something that would last forever, along with the fluidampr.

I'll try to post a follow-up with my experience with it on after some mileage. As for the GM engineers, this engine came from the factory with a litany of problems that were only solved in the aftermarket by experimentation. So it's hard for me to just blindly accept whatever the GM engineers thought was a good idea :). I'm inclined to try some things out and see how it goes, in a case where there is little harm from trying.

Dmax, thanks for such a detailed and thoughtful reply to my original post, I really appreciate your knowledge and willingness to share it with others. All the work I just completed would have been much, much more difficult if it weren't for this forum.

Just an FYI
Clean all the fasteners in the timing case....(Wash threads with Brakleen)
Wash out the cam snout threads too and blow dry.

Use BLUE LOCTITE on the BOLTS when you reassemble the sprockets and the gears.
If anything comes loose....it falls into the chain/gears -----> GAME OVER....

Thanks Robyn. I did use blue loctite on the bolts for the sprockets and gears, so hopefully will be smooth sailing for a long time now. I used permatex high-tack gasket sealer on all the gaskets, I had never used that stuff before but I like it. Much nicer than RTV I thought, it is weird and stringy but it seems to mostly stay put and not just ooze out everywhere and slide things around like RTV. Seems to have worked well, no leaks anywhere that I can see after several test drives now.

My engine is noticeably smoother now, probably due to the fluidampr. Also seems to have slightly increased power, maybe due to the new chain?

A tale of caution to anyone replacing their thermostat. When removing the nut on the stud holding the fuel t-valve drain, I twisted the valve around over the thermostat housing and sheared off the fuel line. Doh! I should have known better, and held the valve in place as I loosened the nut. It was completely hardened and brittle, I could not put it back on the valve fitting it just kept breaking. So maybe it was good anyway to find out before it broke on it's own. But after all the work I had done I didn't feel like more rib-smashing work so I just plugged up the end of the hose for now. Figure I'll replace it in a couple of weeks.

One other thing, my temp gauge now moves around more than before. It used to just be at 210 almost no matter what under normal operation. Now it seems to go just over 210, but also swing back down to 200 or even 195, which never used to happen. Maybe the new fan? Not sure why it would go past 210 first though.

Anyway I'm feeling pretty happy with the results so far. I will see how it goes this summer in the hotter temps and mountain climbing.

i also have a suburban, i found the biggest gain in cooling was removing the soot trap and muffler,. not to mention how it now walks up hills in O/d with out unlocking the converter or loosing speed

I thought I should post an update after another 15k miles and more tribulations.

I ran the "billet" crank pulley for a few thousand miles. It did seem to cause a minor buzz/vibration but only when stopped at a light, otherwise there was no noticeable (to me) extra vibration. I found it annoying enough after awhile to switch back to the rubber dampened pulley. I can see how it might be a fairly subjective thing.

At first I thought my temp gauge swing was due to putting in the wrong thermostat, even though it was an AC Delco and seemed to be the right part number. I switched back to my original thermostat and the gauge stopped swinging around, and was just slightly lower on the gauge than it had been previously. Ended up figuring out that there are at least 3 different delco thermostats that can be used, and one of them looks really different than the others (part number 131-91), which is the one I had originally. Seems like it just works better, so I stuck with that one.

Unfortunately things didn't work out so well this summer. Took a camping and road trip for 7 days starting in Sequoia National Park and ending at our relatives cabin in Big Bear Lake in the mountains outside LA. When we drove up into SNP, the temp gauge climbed up to the 3/4 mark, making me very sad given all the work I had done. It quickly came back down when we made it up there, but then driving up and down within the park the gauge was going up to 3/4 again during any kind of climb. After camping we drove to Big Bear through the Mojave, and it was well over 100 degrees. As we started making the climb up the mountain the gauge started rising, and I had to stop as it got close to the red. It blew out a bunch of coolant. Waited for about an hour and topped off the coolant, and then tried to see if we could make it up the rest of the way, but it was back near the red almost immediately. Ended up having to call our relatives to come pick us up, and left it overnight. Was able to top off the coolant the next day and drive it up the mountain.

After more reading I decided I should clean out the front of the cooling stack, in between the rad and oil cooler and ac condensor. There was some junk in there, but it wasn't all that bad. Then it finally dawned on me based on all the symptoms that I might have a head gasket leak. I went and got a HG leak test kit, and sure enough it indicated exhaust gas in the coolant. Looking back now, I'm guessing it was the HG slowly failing all along that caused my original issues.

I ended up pulling the engine and doing the head gaskets. Replaced the heads with new ones from Clearwater, figured after 200k they were used up and I didn't want to sink any money into testing them. Used studs, since I just didn't feel confident in my ability to properly torque the TTY bolts. I also replaced the motor mount bushings, injectors, glow plugs, and oil cooler lines since there would never be an easier time for those.

That was about 5k miles ago, and so far it's running smooth and strong. The temp gauge still seemed to run higher than what I was expecting, finally hooked up my tech 2 clone to read the temp from the computer, and it turns out my gauge reads just about 20 degrees higher than what the ECT sensor sees. Ended up driving the same road back to Big Bear not long after the job was done, with the computer hooked up so I could watch the actual temp. Never went past 190.

A big thanks to all the people on this forum who have shared their knowledge and expertise on all these subjects and more. I'm not sure I would have attempted the head gasket job without having read all kinds of great info about it here from others who have done it.

Hopefully I will be good to go for any summertime mountain adventures now!

Just a note.

When you get into hard pulls and high ambient temps (Temp gauge climbing some) the fan clutch should engage and the fan noise should become more evident.

If you still have the factory fan clutch ???? might be a good time to replace it.....

If you can get a HD clutch....good plan..

Back in the 80's GM went through a time when the fan clutches really worked well, but owners were complaining about the NOISE....So the clutches were modified sop they did not lock up as tight.....

Then came a lot of the heating issues....

Another spot to think about.

Used radiators gather junk inside the tubes over time that generally can't be flushed out as it is deposited on the aluminum....

A good OEM or better radiator can really make a difference in the heat dissipation ability

If you still have the factory radiator.....might be time to replace that critter......

The cooling system on these rigs is certainly not overkill by any means ....so any loss due to degradation really hurts.

Good luck