1985 6.2 diesel opinions needed!!

[ol'blazer]

so i got a deal on a 1985 k10 with a 6.2.... or i thought it was until i got it home and the engine was blowing back into the rad... im pretty sure its a cracked head, or head gasket..

so this is my problem.. i want this truck as my DD, but i do a ton of winter driving and i wont always be able to plug in, because of my job. at the same time i like the fuel economy of the 6.2.
on the flip side i have a strong running 350 and a 305 that i could swap in... i loose the fuel economy, but im more familiar with them and they'll work better in the winter. what do you guys think?

[Kinze]

Since your location is in the cold North I vote for 350 gas motor, if you lived in the South US and had a good 6.2 I would say go for it but that's not the case.

[ol'blazer]

I like the 350.. but i wonder if i would get a little better economy with a 305..im not sure if it would be worth while.. just a thought

[hatzie]

The 305 will not give you better fuel mileage than the 350.

Winter is not the problem for diesels that people believe. A good compression AMG Detroit 6.2L engine will start right up at -40 with 8 good glow plugs. Pump fuel is winterized starting in mid October in the Northeast US... probably a little earlier in Central Canada.

The worst thing about the mid 1980's GM light truck diesels was that leaky POS Stanadyne 80 fuel filter.

If she runs with a compression leak into the cooling system she is probably in pretty decent shape.
It may just be a blown head gasket. But. Cracks between the valves that extend into the bored coolant passages in the 6.2L & 6.5L heads can be repaired...
http://www.ramengine.com/crack_repair.htm

All that being said. If you're more comfortable with the gasoline motor pull the 6.2 and dump in the 350. Just be sure to swap to the gasoline tranny and torque converter.
The 6.2L can be sold. Just be honest about the compression leak.

[ol'blazer]

Originally Posted by hatzie

The 305 will not give you better fuel mileage than the 350.

Winter is not the problem for diesels that people believe. A good compression AMG Detroit 6.2L engine will start right up at -40 with 8 good glow plugs. Pump fuel is winterized starting in mid October in the Northeast US... probably a little earlier in Central Canada.

The worst thing about the mid 1980's GM light truck diesels was that leaky POS Stanadyne 80 fuel filter.

If she runs with a compression leak into the cooling system she is probably in pretty decent shape.
It may just be a blown head gasket. But. Cracks between the valves that extend into the bored coolant passages in the 6.2L & 6.5L heads can be repaired...
http://www.ramengine.com/crack_repair.htm

All that being said. If you're more comfortable with the gasoline motor pull the 6.2 and dump in the 350. Just be sure to swap to the gasoline tranny and torque converter.
The 6.2L can be sold. Just be honest about the compression leak.

That makes sense, thanks!

what if i swapped out the 6.2 heads for 6.5 heads?

[hatzie]

You can. Two possible downsides.
1 The 6.5L heads may be more expensive and may not be any better.
2 The injector pre-chambers differ by year and displacement.
There are several threads on thedieselpage forum about pre-chambers and the effect they have on fuel mileage and startability. I am no expert on that subject... Fuel mileage is purported to be better on the very early 1982 6.2L engines because of gearing, pre-chamber geometry, and injection pump settings.

If you keep it I'd replace the harmonic balancer pretty much immediately unless the PO has already done it recently. The rubber damping ring dries out and the balancing ring comes loose with predictably bad effects on the crank. They're a wear part that usually only lasts about 100,000 miles.

[Cabnchassis]

Driven the 6.2 and tbi 5.7 side by side for a couple years and the detroit is always my choice for heavy work or super long trips. The 350 is a pretty reliable engine and does the job but my 6.2 is infinitely more trustworthy to me. The simple mechanical injection design and lack of smog parts leaves out most of the things that you have to fix on the 350s commonly.

I laugh at the back and forth over power and reliability on the two. The 6.2 doesn't work as hard doing heavy work as the 350 does but neither one of them has any power to speak of. At the end of the day you can still only do 55 with a trailer so the few HP the 350 has over the 6.2 isn't a big benefit. Grades are slow if you're heavy and pulling with the 6.2 but the 350 is no demon either unless your beating on the pedal making it shift down a lot and motors and trannys don't last long used that way. They both last well if treated well.

Both trucks are 4l80e trans 4:10 gears but the 350 set up that way in my 4x4 which is still half a ton lighter than the dually gets 9/14 city/highway if you put your foot in it all the time it can 8/12 real easy. The 6.2 CC dually gets 14/19 average when it was flat bed, its probably a tad better now I shed a couple hundred lbs at least.

If your charging, starting and fuel systems are in good shape cold weather shouldn't be any worse than any other diesel, esp the times you're able to use the block heater, although I've heard a lot of guys bypassing the glow plug controller to use a momentary switch in the real cold areas.

Also a head gasket is a whole lot easier and cheaper than a fuel system swap if you need the truck on any kind of a schedule. If it's got cracks maybe you have some thinking to do but otherwise I'd change the gasket and roll with it and love it.

[ol'blazer]

Originally Posted by Cabnchassis

Driven the 6.2 and tbi 5.7 side by side for a couple years and the detroit is always my choice for heavy work or super long trips. The 350 is a pretty reliable engine and does the job but my 6.2 is infinitely more trustworthy to me. The simple mechanical injection design and lack of smog parts leaves out most of the things that you have to fix on the 350s commonly.

I laugh at the back and forth over power and reliability on the two. The 6.2 doesn't work as hard doing heavy work as the 350 does but neither one of them has any power to speak of. At the end of the day you can still only do 55 with a trailer so the few HP the 350 has over the 6.2 isn't a big benefit. Grades are slow if you're heavy and pulling with the 6.2 but the 350 is no demon either unless your beating on the pedal making it shift down a lot and motors and trannys don't last long used that way. They both last well if treated well.

Both trucks are 4l80e trans 4:10 gears but the 350 set up that way in my 4x4 which is still half a ton lighter than the dually gets 9/14 city/highway if you put your foot in it all the time it can 8/12 real easy. The 6.2 CC dually gets 14/19 average when it was flat bed, its probably a tad better now I shed a couple hundred lbs at least.

If your charging, starting and fuel systems are in good shape cold weather shouldn't be any worse than any other diesel, esp the times you're able to use the block heater, although I've heard a lot of guys bypassing the glow plug controller to use a momentary switch in the real cold areas.

Also a head gasket is a whole lot easier and cheaper than a fuel system swap if you need the truck on any kind of a schedule. If it's got cracks maybe you have some thinking to do but otherwise I'd change the gasket and roll with it and love it.

I'm not to worried about the power, both a 350 or a 6.2 will do all the work I need. Someone already converted my glow plugs to manual.. Is there a huge difference in fuel economy between the 350 and 6.2?

[Rubble]

Originally Posted by ol'blazer

so i got a deal on a 1985 k10 with a 6.2.... or i thought it was until i got it home and the engine was blowing back into the rad... im pretty sure its a cracked head, or head gasket..

so this is my problem.. i want this truck as my DD, but i do a ton of winter driving and i wont always be able to plug in, because of my job. at the same time i like the fuel economy of the 6.2.
on the flip side i have a strong running 350 and a 305 that i could swap in... i loose the fuel economy, but im more familiar with them and they'll work better in the winter. what do you guys think?

I ran a 6.2 last two winters as a work truck,but it sat in a heated shop overnight & never got shut off if the temp was below 0 degC during the day. As far as the -40 thing without being plugged in,I would never try it or expect it from any diesel.My 24 valve starts WAY better than my 6.2s & even it gets plugged in below -25.

[hatzie]

I've started the CUCV at -40 and the GMC kicks off at that temp as well. Never take the 76 out in the winter so I dunno. They stumble and smoke for a few seconds and then smooth right out.
Plugged in is probably better but they do start at pretty cold nasty temps. You'll actually get heat without driving for 1/2 hour if she is plugged in. I just use an appliance timer set for 1 hour before I take off.

[ol'blazer]

How much would it cost to get the heads magnafluxed?? Would that rule out cracks?

[hatzie]

It should. Most decent machine shops can pressure test for leaks into the cooling passages too.

[Wellgeo03]

Either engine is a good choice. I personally have both. I believe the 6.2 is more reliable, as long as everything on it is in good shape, as the guys above have mentioned. The torque of a good 6.2, especially if you can throw a turbo on it is way better than the 350, and your mileage will increase even more. If you are worried about cold starts, pick up an espar heater, or other brand of circulating diesel fired coolant heater and you will never have a cold engine again. In my opinion the coolant heater is well worth it, especially if you consider what it costs to keep the gas engine plugged in all winter.

I am in Sask, so I know what temps you are dealing with. It was -30C here last night.

[ol'blazer]

Originally Posted by Wellgeo03

Either engine is a good choice. I personally have both. I believe the 6.2 is more reliable, as long as everything on it is in good shape, as the guys above have mentioned. The torque of a good 6.2, especially if you can throw a turbo on it is way better than the 350, and your mileage will increase even more. If you are worried about cold starts, pick up an espar heater, or other brand of circulating diesel fired coolant heater and you will never have a cold engine again. In my opinion the coolant heater is well worth it, especially if you consider what it costs to keep the gas engine plugged in all winter.

I am in Sask, so I know what temps you are dealing with. It was -30C here last night.

Over this weekend it was freezing here too! -45 with the windshield!. And I actually picked up a used webasto heater...Just the wiring is fairly complicated...

[Cabnchassis]

Most 6.2s that are in good shape should beat a 350 on a similar set up truck by at least 3 and as much 5-6 mpg depending on driving habits but there really is no comparison fuel wise. Shoot for a couple years in the 80s they were getting 22 plus out of the detroits in the burbs before they changed some design features. Plus if you drive the 350 hard mileage drops quick. With my 4x4 30" mud tires and 4.10 gears I can easily make it get big block type mileage or worse, out of it if I drive it hard. I drive a lot of city miles so my 350 gets 8-10 most days unless I'm not in traffic. My 6.2 dually will get close 16 around town unloaded. Hooking up a heavy trailer will put the 6.2 down around 11-12 and the 350 8-10 so no big difference towing, but it's huge otherwise.

[Cabnchassis]

Just make sure your grounds and positives are in good shape especially if it's side post. Loose connections and old wires heat up really fast hanging on the starter. Oh Ps while youre down there make sure the back bracket is intact or the starter can break out of the block.

After buying the burb though I'll never not just replace the batteries, grounds, and starter lead. The top post set up has enough connections on the line to maintain but the sidepost setup is just dumb. I was waiting to be able "afford" new top posters and of course was miles from a can of starting fluid when the g plugs wouldn't cycle and I melted the battery terminals in no time ended up having a stranger turn it over for me while I held the bare wires in place like you should never do and it finally kicked but I never want to have to choose between getting shocked and a $3-400 tow again. Plus I was still out for new batteries and wiring cause the whole set up was ruined at the batteries.

[Oregoon]

Personally, I think the 6.2 and the 6.5 got a bad rap. They had their share of challenges, but once the bugs are worked out, they were--are!--long lasting workhorses.

Here's a neat read for you: http://www.thedieselpage.com/62book.htm

[mrolds88]

Had a 86 similar to yours. But it was a 305 truck. with 3.08s. Without overdrive I could make 15.5 mpg with 32s on it.

[Rubble]

Here's what I got with my 6.2 & 350 for mileage. The 82 has the 6.2,86 has 350. Both on 35s with 6" lift & fairly close gearing.In the summer the 6.2 got 18-20,350 was 11-13. Winter the 6.2 was around 15-16,started at 7am & shut off at about 6pm.The 350 was about 10 & not near as much idling.Like Wellgeo03 said,a diesel fired heater is a great investment.Had one on my KW & used it all year round & next to nothing for idling time too...

[86c20]

my c20 with 350 at 65 i get 19-21mpg the k30 with 6.2 at 65 i got 18-20 the 6.2 seems to do better at the higher rpms then the 350. now if it would run so i can drive it agian that would be nice. i have had lots of dumb things wrong with it. leaking pump bad lift pump. bad injectors starter and now after a year of not driving do to moving and work and lack of money she knocks. thinking bad lifter now.

for starting the 6.2. when the plugs died i fond out that it will start on 3 plugs but not 2. and that id you plug it in it will start with no plugs at all. mine at on a toggle. just get the g30?? plugs they are hot and self limiting. i have never had a fail to start in the cold. even after sitting 5 days in new hampshire at 10-15* days and below zero nights. took a bit but started up and that was with 3 plugs and still only 3 15sec cranks. with plugs on

[86c20]

my c20 with 350 at 65 i get 19-21mpg the k30 with 6.2 at 65 i got 18-20 the 6.2 seems to do better at the higher rpms then the 350. now if it would run so i can drive it agian that would be nice. i have had lots of dumb things wrong with it. leaking pump bad lift pump. bad injectors starter and now after a year of not driving do to moving and work and lack of money she knocks. thinking bad lifter now.

for starting the 6.2. when the plugs died i fond out that it will start on 3 plugs but not 2. and that id you plug it in it will start with no plugs at all. mine at on a toggle. just get the g30?? plugs they are hot and self limiting. i have never had a fail to start in the cold. even after sitting 5 days in new hampshire at 10-15* days and below zero nights. took a bit but started up and that was with 3 plugs and still only 3 15sec cranks. with plugs on

[84chevyguyid]

I have an 87 blazer with a 350/700 combo and an 87 burb with a 6.5turbo/700 combo. I have the same wheel/tire combo on both (265/75/16), the blazer averages 14-15 mpg and the burb does 18-20 mpg and has way more power than the blazer. Before having the blazer, I always thought I would convert the burb to a gasser when the motor got tired but after driving both I am glad I have the diesel. Tows things so much easier, drives into a strong headwind great, ect. I make sure its plugged in when it gets zero or below, (F) so its not so hard on it to start. Also helps to run lighter oil in the winter too.

[hatzie]

Originally Posted by 84chevyguyid

helps to run lighter oil in the winter too.

Just run Shell Rotella T6 5W40 year round in everything but the VW. It's a decent priced consumer oil that still has pretty good anti-wear and detergent numbers.
http://www.shell.com/rotella/products/t6.html
5W40 flows better cold than 15W40, it's still 40W hot, and has all the detergents etc needed to carry API "C" ratings.
The latest Blackstone Labs VOA (Virgin Oil Analysis) I can find says they haven't cut the Zinc Dithiophosphate levels too badly yet but they have cut into it some... Zinc and Phosphate #s.
2012 T6 5W40 VOA
http://www.bobistheoilguy.com/forums...Number=2566898
2014 T6 5W40 VOA
http://www.fiestast.org/forum/fiesta...html#post20306

[ol'blazer]

Originally Posted by hatzie

Just run Shell Rotella T6 5W40 year round in everything but the VW. It's a decent priced consumer oil that still has pretty good anti-wear and detergent numbers.
http://www.shell.com/rotella/products/t6.html
5W40 flows better cold than 15W40, it's still 40W hot, and has all the detergents etc needed to carry API "C" ratings.
The latest Blackstone Labs VOA (Virgin Oil Analysis) I can find says they haven't cut the Zinc Dithiophosphate levels too badly yet but they have cut into it some... Zinc and Phosphate #s.
2012 T6 5W40 VOA
http://www.bobistheoilguy.com/forums...Number=2566898
2014 T6 5W40 VOA
http://www.fiestast.org/forum/fiesta...html#post20306

thanks! a friend of mine runs 0w30 synthetic blend in the winter in his 1982 6.2 van..that might be little light.

[hatzie]

Yeah 30W hot is prolly a little light. If there's an API "C" rated oil in 0W40 it'd be fine but 5W is already good to -30F to -35F depending on which chart you look at.
Mobil Delvac 1 comes in 0W40. But. Recent VOA shows significantly lower Zinc Dithiophosphate levels than Rotella T6.