86 GMC K10 Excab

[Rare86]

Hello all, new guy here with a truck I didnt know existed. Ive been looking for a 81-87 Chevy with a 6.2 for a couple of years now and finally found the one I had to have. Its an 86 GMC K10 extended cab. Im not new to the extended cabs of this body style,I have 4 others, but have never seen one with a 6.2. So in my book, I double scored. Truck is amazingly clean, but has a head gasket issue. It started putting water out the exhaust. Im not new to diesel engines, just new to these smaller ones. Ive lived with Cats, and Detroits the last 13 years primarily as an electronics tech.
Question I have is what else should I look for or be aware of? My stepdad had an 83 GMC with a 6.2 when I was a kid, and put over 365000 miles on it with just a few injector pumps and had to install and electric fuel pump. Right now I am just trying to get it back on the road, I'll be searching for power upgrades later, and I hope maybe I can help others down the road as well.

 

[mrbrink]

Thats a sweet looking truck, those extended cabs are rare over here, can't say I've ever seen one before

 

[Rare86]

Thanks,I know theres not very many. I have been looking for about 4 years now and have found pics of a little over 50. I only have been able to actually document about 10 of them. Id say about half of the 50 or so Im not even sure if the are still around, or crushed. No owner info at all. This one is my 5th on and Im ready to get it going.

 

[Rare86]

What are the benefits to replacing the EGR intake for the military style non egr intake? Best exhaust size and muffler for a n/a engine?? I just wanna get the most tunable power out of it for now while Im replacing the headgaskets, later on I hope for the turbo upgrade. I believe its the LH6

 

[RustyBolts]

Was the Extended cab a factory thing, or an aftermarket conversion?

 

[Rare86]

It was an aftermarket conversion like the vans were, and it was sold thru dealers with warranties like the vans as well.

 

[turbonator]

What are the benefits to replacing the EGR intake for the military style non egr intake? Best exhaust size and muffler for a n/a engine?? I just wanna get the most tunable power out of it for now while Im replacing the headgaskets, later on I hope for the turbo upgrade. I believe its the LH6

by replacing the intake you will get more air, thus it is possible to add more fuel... max. 1\8 turn in the pump.... it is possible it is a bad head gasket or a cracked head... its is a fairly common problem, and i suggest using ARP head studs and felpro .010 over thickness gaskets..... start keeping your eyes open for a 6.5l turbo set-up to put on the 6.2, it will come alive with it...

also it is a good policy to change your fuel filter, and wash out your CDR....
when you run the truck with the oil filler cap out, do you have oily steam coming out, if so it is a good sign of blow-by.....

good luck...

 

[Rare86]

Thanks silverfoot, thats the info I was looking for. I'll put the word out at my local junk yards to keep an eye out for a 6.5 so I can snag the turbo stuff. Im almost done getting my shop cleaned out, then I will have it in the shop and start tearing it apart. I may have other questions, but you answered the important one for now. Thanks again

 

[opusd2]

Very nice truck indeed!

As for the exhaust question, so far all I've ever run on my 6.2s were the dual exhaust but on my 6.9l Ford diesel I run a larger than stock single exhaust. I've had pretty good luck performance and mileage wise both ways. But I know with a little experimenting I've done on a couple of gas engine vehicles that a single exhaust works pretty well as long as it's big enough for the scavenging effect on gases. And if you're going to eventually go with a turbo, a single setup will have some of the piping there for you already.

And truth be told in either a single or dual setup, stainless steel pipes makes for incredible sound in my opinion. Check out YouTube for examples and see what you think. And for mufflers I prefer Flowmaster or Magnaflow, but in a pinch a generic turbo works for me.

 

[Rare86]

Thanks alot. Im a flowmaster fan. May go with single 3 or 4 inch since turbo is in the future.

 

[93f250idi]

Very nice truck indeed!

As for the exhaust question, so far all I've ever run on my 6.2s were the dual exhaust but on my 6.9l Ford diesel I run a larger than stock single exhaust. I've had pretty good luck performance and mileage wise both ways. But I know with a little experimenting I've done on a couple of gas engine vehicles that a single exhaust works pretty well as long as it's big enough for the scavenging effect on gases. And if you're going to eventually go with a turbo, a single setup will have some of the piping there for you already.

And truth be told in either a single or dual setup, stainless steel pipes makes for incredible sound in my opinion. Check out YouTube for examples and see what you think. And for mufflers I prefer Flowmaster or Magnaflow, but in a pinch a generic turbo works for me.

mufflers?? never heard of em i personally like straight pipes but flowmasters do have a good sound to em. if i lived in a county where we had to have mufflers then flowmasters would be my choice

 

[milightfo]

mufflers not needed especially with a turbo,gotta let her breath

 

[opusd2]

In my neck of the woods with the ***** cops around, I need a bit of noise reduction. And trust me, I go through a lot of mufflers and research to get the best power out of my beasts.

I have one project that I am working on now and doing some fitting, running, changing, and running again. I build the exhaust to match the motors and their intended purposes.

 

[otisd85]

on my truck the exhaust was just about falling off it was rusted so bad before i put the banks turbo kit on it and was obnoxiously loud! after the turbo install though i drove it to an exhaust shop with only the down pipe and it was considerably quieter than the duals from the factory, after i got the 4" from the down pipe back put under it now you can here the motor rattle over the sound coming out the tail pipe although it does have a bit of a cackle from about 2100-2400 rpm when under a load. still after the turbo install i dont think a muffler would be necessary, but if for some reason its louder than you like it would be easier and cheaper to cut out a piece of pipe and add a muffler later than to buy a muffler now then delete it later and have a muffler laying around that you didnt have to buy. but thats just my opinion and if you ask my ol'lady my opinion dont count!

i was on my way up to lansing iowa last spring for work and i seen an ex cab sittin out to pasture along side a barn that was half caved in off the highway a little ways. i could have swore it was a chevy as i drove by, but convinced myself it had to be a dodge as ive never seen a pre '88 ex cab chevy so i didnt bother going back to look at it. i dont think words can even explain how bad im kickin myself in the ass now for not going back to make sure!!!

 

[Rare86]

These trucks keep people guessing all the time.I have bad people call me a liar when I talk about them, and have had to start carrying a photo album with me for proof. Ive been to shows where people have walked by it and said little, then on the return trip, they fall all over themselves trying to get a better look. Its funny.