kagefighter
Registered User
This is going to be an absolute novel of a post but I've done a fair amount and I'm at a loss.
I bought a low mileage (75,000 miles according to seller) 86 f350 with a 6.9idi banks turbo (nonwaste gated) c6 rear wheel drive dually. When I bought the truck I immediately noticed it didnt feel to have nearly as much torque in the low end (1500 rpm and under) as my 88 f250 with a 7.3 and a zf5. Both trucks have the same rear diff ratio (3.55). I figured it was just the c6 and a torque converter that just didn't have a low enough stall speed and moved on. Otherwise the truck ran super smooth, turbo produced boost like expected (about 9 lbs wot), c6 shifted as expected.
As I owned the 6.9 truck I noticed a few things, it didn't start as quickly as my 7.3, it would blow a notable cloud of white smoke at start up, when towing or under heavy throttle while driving unloaded there was a noticable but not obnoxious amount of black/grey smoke from the tailpipe, and the fan clutch would come on fairly frequently on the highway and always corresponded to the dash temp gauge climbing to the right side of the 'M'.
My glow plug controller was short cycling. Even on a cold day it was on for only 1-2 seconds. I decided I needed to replace my glow plugs and glow plug controller. Ended up getting motorcraft plugs and a "solid state 6.9 controller" from accurate diesel.com. The glow plug controller turned out to be a disappointment but the truck is substantially improved and starts fairly quickly with less white smoke.
With the cooling system, I started by having it coolant system flushed and coolant changed. Didn't fix the frequent fan clutch engagement/temps creeping up problem. Then replaced the thermostat with a motorcraft thermostat. Seemed better but still having the fan kick on more than it should (this always happened unloaded on the expressway at speed). Developed a radiator leak. Replaced the radiator, another motorcraft thermostat, fan clutch. Problem was substantially better but still had a tendency to want to run hot if I pushed it at all on the highway and still felt weak in the low end.
Next I got a DTI 3300 timing setup. Engine was timed at like 6 BTDC @2000 adjusted to 8.5 BTDC @ 2000rpm. Sounded more rattly but did not honestly make a significant change in performance. Didn't change anything with the running temperature. Black smoke under load interestingly seemed a little LESS noticeable but was still present under heavy load.
never liked the C6 I decided maybe the heat from the transmission is setting this fan clutch off and just adding heat to the system. Ended up doing a ZF5 swap which went well but the turbo piping was a PITA because I had the older banks with a driver side up pipe.
The fan clutch hasn't kicked on since the swap but it's been colder out and I haven't been towing so maybe it's better, maybe not.
At this point I feel like I can pretty directly compare these 2 trucks I own. The 6.9 with the banks feels substantially weaker under 1700 RPM than the NA 7.3. This is not how I drive normally but as an example, with the 7.3 I can easily start from a stop without adding any throttle in second gear. If I do the same thing with the 6.9 it feels like it might stall. Also just in general the 7.3 feels very peppy in the low end and the 6.9 feels like a dog until the turbo starts to spool.
One last thing I did was delete the banks air filter/ intake hat combo for a more free flowing air intake. That made the engine much more responsive but it remains "weak" in the low end. I am also going to rework my up pipe to make it more efficient at some point.
What do you guys think?
At this point I feel like it's got to be a worn out engine even though it's supposed to be lower miles, worn injector/IP, fuel turned up too much?, or maybe this is the way a turbo'ed IDI is supposed to feel?
I bought a low mileage (75,000 miles according to seller) 86 f350 with a 6.9idi banks turbo (nonwaste gated) c6 rear wheel drive dually. When I bought the truck I immediately noticed it didnt feel to have nearly as much torque in the low end (1500 rpm and under) as my 88 f250 with a 7.3 and a zf5. Both trucks have the same rear diff ratio (3.55). I figured it was just the c6 and a torque converter that just didn't have a low enough stall speed and moved on. Otherwise the truck ran super smooth, turbo produced boost like expected (about 9 lbs wot), c6 shifted as expected.
As I owned the 6.9 truck I noticed a few things, it didn't start as quickly as my 7.3, it would blow a notable cloud of white smoke at start up, when towing or under heavy throttle while driving unloaded there was a noticable but not obnoxious amount of black/grey smoke from the tailpipe, and the fan clutch would come on fairly frequently on the highway and always corresponded to the dash temp gauge climbing to the right side of the 'M'.
My glow plug controller was short cycling. Even on a cold day it was on for only 1-2 seconds. I decided I needed to replace my glow plugs and glow plug controller. Ended up getting motorcraft plugs and a "solid state 6.9 controller" from accurate diesel.com. The glow plug controller turned out to be a disappointment but the truck is substantially improved and starts fairly quickly with less white smoke.
With the cooling system, I started by having it coolant system flushed and coolant changed. Didn't fix the frequent fan clutch engagement/temps creeping up problem. Then replaced the thermostat with a motorcraft thermostat. Seemed better but still having the fan kick on more than it should (this always happened unloaded on the expressway at speed). Developed a radiator leak. Replaced the radiator, another motorcraft thermostat, fan clutch. Problem was substantially better but still had a tendency to want to run hot if I pushed it at all on the highway and still felt weak in the low end.
Next I got a DTI 3300 timing setup. Engine was timed at like 6 BTDC @2000 adjusted to 8.5 BTDC @ 2000rpm. Sounded more rattly but did not honestly make a significant change in performance. Didn't change anything with the running temperature. Black smoke under load interestingly seemed a little LESS noticeable but was still present under heavy load.
never liked the C6 I decided maybe the heat from the transmission is setting this fan clutch off and just adding heat to the system. Ended up doing a ZF5 swap which went well but the turbo piping was a PITA because I had the older banks with a driver side up pipe.
The fan clutch hasn't kicked on since the swap but it's been colder out and I haven't been towing so maybe it's better, maybe not.
At this point I feel like I can pretty directly compare these 2 trucks I own. The 6.9 with the banks feels substantially weaker under 1700 RPM than the NA 7.3. This is not how I drive normally but as an example, with the 7.3 I can easily start from a stop without adding any throttle in second gear. If I do the same thing with the 6.9 it feels like it might stall. Also just in general the 7.3 feels very peppy in the low end and the 6.9 feels like a dog until the turbo starts to spool.
One last thing I did was delete the banks air filter/ intake hat combo for a more free flowing air intake. That made the engine much more responsive but it remains "weak" in the low end. I am also going to rework my up pipe to make it more efficient at some point.
What do you guys think?
At this point I feel like it's got to be a worn out engine even though it's supposed to be lower miles, worn injector/IP, fuel turned up too much?, or maybe this is the way a turbo'ed IDI is supposed to feel?
