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More Power
02-14-2011, 11:43
What follows is a two year old email exchange I had with a member who was at the time a Christian Missionary and 6.5 owner serving in Africa. Jon is an engineer working to improve irrigation and farming practices and his wife is a nurse, serving in a local hospital. Their services are free to the host country.




What an awesome resource. If I may, I would like to request some advice. I am a missionary in Kenya, East Africa. A friend is returning to the U.S. soon, and I need to order whatever I might need, think I need, want, or can afford. It's a one chance shot. If I start pulling this engine apart and find I need something, I will be waiting 2 - 4 weeks for an “overnight package”, if I'm lucky. Here goes...

I have an early 1996 model-year K3500 6.5L TD with about 100,000 miles on the odometer. Due to the slow off-road driving with a loaded truck and trailer, the mileage doesn’t reflect the number of hours of driving. This makes the wear twice or more what the mileage would imply. Ten years in Africa is hard on a truck. We also have very high sulfur, low quality motor oil and sometimes dirty fuel. I use a 15W40 CH5 motor oil blend formulated by Cat USA for Kenya Fuel, which is produced locally. I change the engine oil about every 50 to 75 hours of use. This is the best oil sold locally without going synthetic. I’m sure this oil doesn’t measure up to Rotella. I service the vehicle regularly and have upgraded the air intake to that used on 1998 model year 6.5 trucks.

The truck has been experiencing progressively worse engine heating problems. I don't notice it so much in the engine temperature gauge, but as a lack of power on hills that I pull with common loads every month. The oil also appears to be breaking down more and I have now lost two PMD (electronic fuel injection pump driver modules) units in a year and a half as well as the fuel injection pump itself and the vehicle ECM. Yes, I pulled and cleaned the Radiator, might be a poor exhaust as it has some dings from rocks and needs to be replaced. The catalytic converter has been removed long ago. The fuel injectors and fuel lift pump / PMD were replaced together in 2005.

Recently, the engine experienced a collapsed valve lifter; at least I think that’s what it is. I heard some serious knocking on start up when the problem first appeared. I don't want to pull the engine until I have all the parts to do it right. I have the ticking in the engine and very dirty oil. I am changing the oil every trip and using cleaners. I have had the valve covers off, but couldn't find anything that appeared to be out of order. I am also replacing the truck’s frame, and doing major overhaul work on the whole truck. I am trying to get the parts in time to do this all together. My truck is my security for myself and my family. I don't want it down for any longer than it needs to be.

I have ordered new cylinder heads, head bolts, gasket sets, PMD relocation unit with new PMD and #9 resistor, dual thermostat cooling kit with 9 blade 21" fan, new larger oil cooler lines with new and a larger cooler, and lastly a 4" exhaust system. When I do rebuild the engine, I will replace all bearings, rings, lifters, rollers, and add better fuel filtration / Racor. I have a few questions that I would like your help with.

Do you recommend the Phaser dual-idler gear-drive timing set from Diesel Services Group in place of a new timing chain, and does the stud girdle kit from DSG work in increasing the strength of the lower end?

Would you recommend 18:1 pistons in my position? Will they work without any other engine modifications or do I need a new waste gate / or computer program / or ? to increase boost? I would be ready to do more at a later date, but I am at the end of my resources with everything I’ve planned so far. I don't have access to salvage / junk yard parts, but will need to order off-the-shelf kits and parts. I would like the internal engine modification completed, and then add parts later on as the situation dictates.

I am most concerned with improving engine reliability and lowering coolant temperatures, although having a little extra power to make it over the hills would be nice if I don't lose reliability. I travel over several mountain ranges that can reach 8000 ft. with multiple ups and downs to reach Nairobi for supplies. Our weather here can be somewhat variable, but usually quite warm. I have seen the temperatures reach 40 degrees at night only one time, and about 50 degrees once a year for a month at night. The rest of the time is hot, with 60 degree nights and 100+ days. Sometimes it can be in excess of 120 degrees air temp. The paved roads will literally cook, and can melt the tar out of the asphalt, leaving just the gravel. I am willing to look at anything that helps with cooling and reliability, and that is what led to the 18:1 compression ratio piston question. You have written before about lowering the factory compression ratio of 21.3:1 to 18:1 to help improve engine durability. I am thinking it might be best / safest to also to install an aftermarket the cam and to have a spare piston on stand-by just in case. I have written our mission regarding these last two thoughts and am waiting on their advice.

The shop services available to me here in Africa can be both great and awful at the same time. You can get anything done for a good price, but the quality of any precision work can be very poor. The chance of finding a local shop that does a good job machining an engine block is like rolling the dice. Because of this I won't be getting cylinders honed or have the crank turned. Obviously, balancing is out of the question. I think that gives you all the info I can give you on where I am with my rebuild. Like I said, reliability is the first, last and only requirement. New trucks have a 100% duty / tax / shipping cost increase, so that is not an option. I am hoping to get at least 10 years more out of this truck. I would like to see the odometer reach 250,000 miles. I have most of the tools needed, including a Tech II scan tool for setting the injection timing and diagnostics. I am fairly skilled at this sort of work, but have little experience with the internals of the 6.5. I do have help available from other missionaries in the area, but I trust myself most. I don't have an exhaust temperature or boost pressure gauge yet, but they are on my wish list.

Make: GMC
Model: K3500
V.I.N. 1GTHK39FOTE51xxxx
Engine size 6.5L Model F Ser. No. TIE676694
Glow Plugs - 9G
Fuel Injection Pump Make Stanadyne Nov. 03 Model Electric
Injector pump replaced 20 March 2005

Thanks for the time. Any help would be appreciated. If you don't want to commit to a recommendation, that is okay. Sorry that this has gone on to such great lengths. I just wanted you to have all the information available that might help. Thanks again.
Jon J.
Kenya



Continued next post:

More Power
02-14-2011, 11:45
Here was my reply from 2 years ago:

Hi Jon,

Amsoil (www.amsoil.com) and Filtration Solutions (www.fs2500.htm) both offer excellent dual-bypass engine oil filtration kits for the GM/Ford/Dodge diesels. Additional oil filtration would allow you to run a fully-synthetic for 2-3 times more miles than what a quality petroleum motor oil (like Shell Rotella or Chevron Delo 400) would allow. For a synthetic, Royal Purple, Mobile Delvac 1, Shell Synthetic or Amsoil marine synthetic would all be good choices. Lifter collapse is usually caused by excessive soot in the oil or due to using a motor oil that is not API (American Petroleum Institute) rated for diesels. The right API oil that carries the rating of CG-4, CH-4, CI-4 or CJ-4, and changed regularly is the best defense against lifter problems and a long engine life. The API ratings indicate the oil’s ability to deal with soot. The first letter in the rating (C) indicates a “Compression Ignition” (aka diesel) rating.

With diesel fuel that isn't as clean as you'd like, additional fuel filtration would be a good choice. The electronic Stanadyne DS4 fuel injection pump is somewhat susceptible to poor fuel quality. Auxiliary diesel fuel filters and complete assemblies from Racor, Parker, Wix, Baldwin, FASS and others can be obtained from a variety of advertisers here in The Diesel Page. The GM factory Racor fuel filter used on the 6.5L diesel is rated for 10-micron, which may not be the best choice if your fuel supply is less than optimum. A 2 or 5-micron secondary fuel filter would be recommended for your situation.

Most owners don't realize how important the fan-clutch is to cooling system performance. I suspect your fan-clutch might need to be replaced if you’re not hearing it engage when the engine temperature exceeds 210 degrees or while pulling away from a stoplight with the air conditioning on. You should hear the fan “roar” during those times. The larger 21” Duramax fan will be an improvement, but you’ll need the 1997/98 6.5L diesel fan-clutch to match the bolt pattern used on the newer Duramax fan.
If you need to replace the Pump Mounted Driver (PMD) module, I'd suggest the one offered by DTech (www.dtechproducts.com), which is a completely re-designed electronic module that is currently recommended by GM as a direct replacement for the original Stanadyne module. So far, I haven’t heard of a DTech failure.

Diesel Service’s (www.dieselservices.com) Phaser Dual-Idler gear drive timing set is a nice addition to the 6.5, but in practical terms, it'll not make all that much difference for your use when compared to a new timing chain. I'd recommend installing a new chain and sprocket set, and save the $300 difference. The gear drive does help improve performance while on the highway and it’ll never wear out, but your slow speed driving might not see a benefit. The new viscous harmonic damper offered by Fluidampr (www.fluidampr.com) for the 6.5 would be a worthwhile investment. Low engine speeds can generate more harmonic energy in the crankshaft, which the Fluidampr deals with more effectively than the factory crankshaft damper.

The vehicle computer manages boost pressure in the 1994 or newer electronic 6.5L diesel equipped trucks. A variety of vendors offer performance oriented programming to increase power. These programs include turbo wastegate management, so boost pressure will increase as well. However, for your low-speed use, I wouldn’t recommend performance programming, but rather concentrate on making the factory systems work as well as they were designed to. This will simplify any future service work and could provide more long-term reliability.

The stud girdle offered by Diesel Services would add a little confidence, so if it's in the budget, I'd get one. Before spending any money on a rebuild, be sure to carefully examine the main webs in the block, looking for cracks.

I would not recommend 18:1 pistons in your situation. The lower compression ratio is most beneficial when the engine is run nearer to its power and torque rating for longer periods of time. Slow speed driving won't benefit from lower compression. Lowering the compression to 18:1 wouldn’t necessarily affect the low speed drivability of the engine, but it’s just not necessary unless you’re working the truck hard. The factory compression ratio of 21.3:1 allows for cleaner and smoother cold starts.

The factory camshaft is just fine, and I wouldn’t recommend anything else. To date, there isn’t enough dyno or performance data (none that I know of) to support a need to experiment with an aftermarket camshaft.

I see in your note that your 6.5L diesel is still equipped with the ACDelco 9G glow plugs. These were discontinued in the late 1990’s, and eventually replaced with the currently recommended ACDelco 60G glow plugs. The 60G glow plugs are thermally self-limiting, and won’t burn out if a problem develops with your glow relay. The 9G plugs will burn out if powered longer than about 15 seconds, and can lose tips as a result, which could require removal of the cylinder heads to extract any loose tips.

Setting the injection timing requires a Tech II scan tool. Let me know if I've missed something or if you need the timing instructions. Glad to help!

NH2112
02-14-2011, 20:59
Personally, in that environment I'd ditch the DS4, PMD, & computer completely and have a DB2 calibrated for the same power curve. An aftermarket boost controller would be necessary, or there's always the perfectly-serviceable-but-not-very-elegant solution of welding the wastegate closed like the PO did with my MFI '99 6.5l. You'd just have to closely monitor boost & EGT and lighten up your right foot.

I'm not a very big fan of electronics in rough environments, no matter how rugged they make them they're never as rugged as a lack of electronics! :D