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Top Tech Questions - You've Got Questions? We've Got Answers!

Welcome to Top Tech Questions. Oftentimes, readers contact us with questions about articles, or to praise us on what a good job we are doing. But our favorite form of reader communication is tech questions. So we're introducing our Top Tech section, a place where you ask what's on your mind, and we answer it. Got a trouble code? Wondering how to get your engine to make more power?

Send us an email at jason.sands@sorc.com and we'll do our best to answer it.

Q: Want To Drive A 6.5LI'm a die-hard Chevy fan and I'm looking into buying a 6.5L turbodiesel. My question is: are there any certain years I should try to get my hands on? What about performance upgrades? My intent is to put some money in it right off the bat to upgrade the cooling system and then pursue additional power. I know the truck will never really be able to compete with the modern-day diesels, but I'm willing to live with that.

Donnie Bullock
Clinton, Missouri

A: The 6.5L engine is by no means a powerhouse, and its injection system is limited as far as performance potential goes, so it's time to seek outside help. Back before aftermarket parts were readily available, diesels had to rely on injecting propane, a water-methanol mix, or nitrous oxide to make power. Since nitrous is more of a competition-only modification, we'd suggest propane or water-methanol as a power adder. A lot of people bash propane, but we've ridden in a few trucks that are on the 'pane, and we can tell you it makes one heck of a difference. Count on adding about 40 to 80 hp depending on how much you inject. Going the water-methanol route not only means more power, but a lot lower EGTs when towing with your truck. If you don't like the idea of having to carry around a bottle to make power, Heath Diesel (phone: [877] 894-6266 or visit www.heathdiesel.com) offers a line of performance packages for 6.5L-equipped rigs. Prices range anywhere from a few hundred bucks to a few thousand, so there will be a kit within your price range no matter what your budget is. Another good resource is Kennedy Diesel (phone: [715] 255-9433 or visit www.kennedydiesel.com), a 6.5L guru that sells lift pumps, tuned ECMs, and more. As for a year to buy, we'd shoot for a '97-and-up model. They have oil-cooled pistons, a revised, higher-capacity cooling system, a better turbocharger, and more performance potential. We'd expect to pay about $3,000 to $6,000 for a low-mileage truck in decent shape. Depending on the area you live in, you may be able to find one cheaper. Even with a few modifications, don't expect any more than about 200 hp at the wheels. If you're willing to live with that, then go nuts. There are many 6.5L trucks out there just doing their daily diesel duties, and fuel mileage is often in the 20-plus-mpg range with trucks equipped with 3.42:1 axle gears.

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5 comments
chrisscalf2
chrisscalf2

i have a 1995 chevy 3500 6.5 deisel it runs fine but it stalls going down the road and starts back up when i turn the key off and turn the key back to start  it does it several times a day and sometimes it doesnt do it at all wat can i check

dantambo
dantambo

I have a 1999 chevy i ton pu w/the 6.5 tubo diesel motor and auto trans,it only heats up towing 10,000 lbs or so over hills and loose power when hot??

gerry822
gerry822

i have a 1998 6.5 turbo, at times at start up, the engine revs to a high rpm on it's own.  Is there anyone out there that has had this problem?

beehive
beehive

I have a 1993 6.5 and when I get to a corner it also quits , I think it has something to do  with engine oil pressure , when it is too low it cuts out the fuel pressure. The only way it will start again is , I installed a fuel pump manual switch in the truck and I turn it on after it cuts out then it restarts, when I am going again I switch it back off. I changed the fuel pump relay and a new oil pressure switch , and it still does the same thing at corners.

Lawrence Najolia
Lawrence Najolia

I HAVE A 1990 CHEVY  TRUCK WITH A 6.5  WHEN I PUT THE A/C ON THE TRUCK KILLS SOMETIMES IT TAKES A LONG TIME & SOMETIMES IT KILLS RIGHT AWAY WHAT CAN I CHEECK TO STOP IT FROM KILLING ON ME BUT IT ONLY KILLS WHEN I COME TO A STOP  THANKS FOR YOUR HELP ON THIS

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