What are common big deal breaker issues with 6.9? Someone bringing one in today they want to buy. Going to give it a quick look over.
Common 87 6.9 issues?
- Thread starter Danielle
- Start date
That's the best year many say. 6.9 with the newer 7.3 style flow plugs, possibly a 5 speed if manual. No real major issues other than the standard fuel leaks and age of parts
Silver Burner
Burnin' Oil&Rubber
Yup. 87 6.9's are great. Newer brick-nose style and nicer interior, better GP system, and possible 5-speed on a 6.9L. Thumbs up!
icanfixall
Official GMM hand model
Well... If it really is the last year of the 6.9 engine then it would be the one to buy but. You will need to post the block serial numbers for us to be able to class this engine as what you say it is. The first 7.3 engine serial number was 500,079 and went up to 1,116,330. The turbo block started at 1,116,331 and up from there. Some were turbo and some were not. A turbo block has 1/4 inch port ports in it where all 6.9 and 7.3 non turbos had 1/8 inch oil ports. For me the biggest concern with a 6.9 or any year is the small 7/16 head bolts but we all know those can easily be upgraded to ARP studs.
This would have been a gem, but on road test.... only one gear! (Automatic). Customer wants something to haul trailer full of cement 
Wyreth
Certifiable Noob
I HAVE one of those. Never had an issue with the motor. Had to replace the GPC when I bought it. The 6.9 has been epic. The c6 behind it..... not so epic.
I have a C6 behind my 6.9s (at the moment) and the one I use for heavy hauling had to be rebuilt about 14 years ago. But it was a farm truck and had been abused greatly, so when it was built my folks had the thing updated with a shift kit and better internals. With the synthetic fluid I run and extra cooling, I have never had an issue. And it also passed the "Craig" litmus test, so it has to be tough. That's a big reason I bought it.
* Since I often refer to my brother being a good indicator of whether or not something is well designed, built, or just plain mean - well if you knew how he doesn't maintain any vehicles (or equipment really) that he owns or uses, just repairs when it goes all tango uniform, you'd understand my reference. The kid is harder on vehicles than 20 years of winter salt. I guess I don't need to mention that he is a diesel mechanic with a degree in such...
Anyway, just my opinion on C6's. I think they are plenty tough and reliable, just not exactly mileage friendly with 4.10s and the superslab.
* Since I often refer to my brother being a good indicator of whether or not something is well designed, built, or just plain mean - well if you knew how he doesn't maintain any vehicles (or equipment really) that he owns or uses, just repairs when it goes all tango uniform, you'd understand my reference. The kid is harder on vehicles than 20 years of winter salt. I guess I don't need to mention that he is a diesel mechanic with a degree in such...
Anyway, just my opinion on C6's. I think they are plenty tough and reliable, just not exactly mileage friendly with 4.10s and the superslab.
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