Have an '85 K5 Blazer with a 6.2L diesel that is in great condition. Motor is very strong and healthy. I use this truck to pull a 26' cabin cruiser that when full of gas and water and gear and all can weigh up to about 7200 lbs. Truck pulls it fine, but I am not going to win any drag races while attached to this boat. My questions and concerns are this. As some of you may know, these trucks have huge radiators and the lines for cooling the motor as well as the tranny run through it and all. Although when traveling up a hill, it seems my gauge goes up more than it should faster than it should. Radiator is fine, tranny is almost new. I thought about adding a tranny cooler, but not sure if that would help. Now am thinking of adding a better thermostat. Any recommendations or anything I can do here. Sometimes have to pull over more often than I would like to, to let temp gauge go down. Secondly, even though this truck pulls it fine on flat roads and slight hills, when trying to go over mountain passes, it seems that the truck should pull it faster than it does. Typically slow to about 25-30 mph. I have a K&N air filter and thought about adding a Banks system, but don't want to spend that. Is there anything I can do to help in this area? Thanks for taking the time to read this. Hope to get some help here as I have in the past. Thanks again.
Good to hear, treat it nice (your not) and you'll have it for the rest of your life.
Thats not a light load.
Not a good thing, that.
I'll tell you how to keep it that way.
Trust me, it will.
Wouldn't be a waste of money.
That engine has something like 165HP @ 3500 RPM. That's a 305CUI gas engine. It has a little more torque then a 350 can produce though.
Junk. If you like your engine strong ditch that.
Many consider this a must add - like tires and oil.
This is TranSurgeon's procedure, I can't take the credit for this piece of work.
"Here's a piece I wrote some time back for the dodge truck group
It applies to GM products, except the part about swapping oil pans
"well, at the risk of calling down the wrath of those who disagree with my philosophies about transmission coolers in general and truck transmission coolers in particular, here goes:
If you are towing any load at all, you need a cooler.
If you are towing a small load, you need a medium sized (Hayden 1678 or Tru-Cool 4490) cooler
If you are towing a medium sized load, you need a big (Hayden 1679 or Tru-Coool 4590) cooler
If you are towing a large load, you need a pair of Hayden 1679's or Tru-Cool
4590. plumbed in parallel.
These should be mounted in front of the A/C condenser, as close to the grille as possible; this may take some time to build the necessary brackets. Mount the cooler(s) at 4 points, they are subject to a lot of vibration from the airflow thru the grille. Check frequently that the cooler will not touch the grille, contact will 1) eventually break the grille, and 2) drive you up the wall on a long trip.
Plumbing it up:
We ALWAYS eliminate the factory radiator oil cooler from the circuit. Always. Usually an ifra-red detector scan of the finished installation, after a pretty brutal road test on a rebuilt unit, will show the following temps:
Cooler inlet = 140-160 Cooler outlet= about 20-30 above ambient (80-90 on a 60 degree day) Pan = about 120-130 depending on how much fluid the pan holds.
I know, I know, there are those who claim that if you do that, that the ATF will 'gel' at low temperatures. For those, I'll just point out that the 'pour point' of ATF is -71F and move on.
When you eliminate the factory cooler, you will have to cut the existing lines and go to hose. First: NEVER use a hacksaw to cut the lines. Use a tubing cutter. Second: Having spent a couple hours mounting the coolers, here's where a lot of people get in a rush and say 'good enough' instead of taking the extra measures to insure a good installation. Mounting the coolers is easy, insuring that the plumbing will stand the acid test of a long road trip is not difficult, just time consuming:
1) Sharp edges on metal partitions through which the hoses pass: these work at a hose over time, but rest assured, it will cut thru on a mountain road, at 11 at night, in a blizzard or downpour, with the wife and kids in the truck. Count on it. Where the hose goes through a metal partition (radiator support, usually) take a length of 5/16 hose, slit it lengthwise, and make a grommet to line the hole. Use plastic wire-ties (I recommend 'IDEAL' brand from an electrical supply house, they are tougher in bad environments) to secure the hoses to each other and to support points; make one if you need one and there isn't one handy.
2) Transistion from hose to metal lines: Before you start the project, check with your local NAPA or CarQuest to see if they have the machine and fittings to crimp hydraulic-style connectors on hose. When you find a place that does, have them make up ends for your hoses with a hydraulic fitting that has a compression sleeve to accept the metal line.
3) Cooler 'kits' are woefully short on hose. Stop by a transmission shop and pick up about 6 extra feet. Then have your connectors crimped on THAT piece and the piece that came with the cooler. Now you can connect up to the metal lines first, then hook up to the cooler after measuring how much you need (no running short by 2" under the truck on a Saturday night at 9 o'clock).
4) If you use a pair of coolers, plumb them in parallel, not series. Use brass barbed Tee's for the junctions, run the lines to/from the transmission into the stem of the tee, and the lines to coolers to the 'top bar' of the tee. That makes flow restriction due to elbows equal for both and equalizes the flow.
5) Good quality hose clamps are a must. I find the ones supplied with the coolers have too much 'left-over' after tightening, that piece sticking out is just waiting to slice someone's (yours, probably) hand open. I use 'Ideal' (not the same company that makes the wire ties) number 5203's, they work just right for the hose in the cooler kits. The instructions say NOT to double clamp, but if you arrange the clamps with the screws on opposite sides of the hose, two will fit nicely if you lube the hose and get it all the way onto the cooler fitting. Try to arrange the clamps so you can reach the screws with a 1/4" socket on a long extension thru the grille.
6) Don't put the grille back in right away, run it till the fluid gets warm (with no load, it won't get really hot), then snug down the clamps. Don't overdo it, watch the little 'slots' where the screw rides, when the hose material is just sticking up thru those slots, its tight enough. After you're sure its fluid-tight, then put the grille back in.
If you have the NON-overdrive transmission (A727 or A904) you can order and install an oil pan for the matching overdrive unit (A518 or A500), which will give you a couple extra quarts of fluid capacity.
Hope this helps. Take your time, don't rush the job, always think in terms of 'how can this part screw up and leave me stranded?' and out-think it. Your transmission will thank you for it.""
Normal thermostats do not open very far (you will see what I mean when you take out the old one and compare it to the new one) so they have restricted flow, under normal conditions this is not a problem but you are (way) over taxing the truck so you are not getting enough coolant to the engine. Upgrade to a high performance thermostat (flow more water) of the same temp (190-195F). Don't go cooler, diesels are heat fired engines. Cool it too much you will loose power. Also, when you get the middle (or a little more) of the temp gauge you should hear the fan kick in if not then also replace the fan clutch.
Tow in 3rd unless the road is flat. You will get more power in 3rd (1:1) as opposed to 4th (.74:1) since you are towing with this truck you probably already know this...
You absolutely need a trans cooler and as soon a possible. Get the biggest you can find!
These (like most diesels) run better with better diesel. I have found that with my 83, 6.2 I could actually tell the difference between cheap diesel (40-45 cetane) and premium diesel (50+ cetane). With better diesel the engine will have more power and will run cooler. You can also see this in the Ford Powerstrokes. The lower quality diesel the more noisy they are...don't know this relationship with the Duramax's.
Like said elsewhere these engines were meant for good fuel economy. They are taxed during heavy towing. My 83 6.2 is rated for 130hp at
3600rpm, and I like you pulled a 27ft trailer (55 max speed) and a 24ft boat (45 max speed) with a 3.21 rear...
Up hill pulling at 25-30mph is about right. Once took the 27ft trailer through the Tennessee mountains (never again) second gear, floored the best we could do was 20mph. Burned 30gal of diesel in a little more then 40 miles. Luckily a trucker in a Freightliner felt pity and pushed us up one hill or we would have never made it. (yes, we were idiots!)
Good luck, these are nice trucks (in fact I'm looking for a diesel Blazer to rebuild, they are very rare). Of course all of this is my opinion but I think I am accurate and since it would cost less then $50 to make the upgrades you have nothing to loose.
:-) The metal fan connected to the water pump is connected via a viscous coupler filled with silicon. When the silicone reaches a certain temperature it thickens and the fan starts to spin at engine speed. When I kicks in it sounds like a jet engine, can actually suck a piece of paper to the front grill. When cool the silicone is very fluid and the fan just turns but not very fast. Sometimes the silicone leaks out or what ever and the fan does not engage. So you are getting no or little pull of air through the radiator. If you have a high perf thermostat already installed then check the fan. If it is ok then change the radiator. Nothing else left to check....
The mid 70's to the early 90's (full size) blazers were offered with the 305 as a base model or 350 and 6.2 (379cid) as options. The 6.2 is not a converted diesel but a true diesel designed by Detroit Diesel in the late
70's for use in delivery trucks and other light duty truck applications. The 6.5 diesels would displace 387 or 389 but are also true diesels not conversions. So you chilton manual is wrong. I think mid 70's and earlier may have offered a 389 or 289 or what ever, don't know before the time I became interested in cars.....
An extra fan would not help just check the fan clutch to make sure it is working. I am sorry to hear the cooler would be more then $50 the last time I bought one it was in the $30's for a nice 18k lb cooler but that was 12 yrs ago. There is no reason you can't install it yourself. Go to Pep-boys or any auto parts store and get one as a kit and a few extra clamps. On the truck you will see the trans lines (stainless steel lines) going into the back of the radiator, passenger side about half way up from the bottom. Start the truck and let warm up and see which one is cooler. The cooler one is the outlet. Unhook this one and slip the hose *coming* from the cooler over the flair, double clamp. In the kit will be a brass fitting that will screw (use a little Teflon tape on the threads) into the opening of the radiator that you just disconnected the trans line from and slip the hose
*going to* the cooler on this fitting. So the flow is from trans to radiator, out of radiator into cooler, out of cooler back to trans... You will find two small holes drilled into the radiator mount right next to where you are working. Slip both hoses through those holes. Pull off the plastic grill and find a place to mount the cooler. It will use plastic zip ties and connect to the AC condenser. You may have to remove the upper radiator shroud but that is easy just a couple screws on the sides and one on each side about half way down (engine side). The shroud is in two parts, you may only need to remove the upper part to be able to get your hand between the condenser and the radiator. Hook up the hoses any way you want to the cooler. Start the truck, check for leaks, top up the trans oil and install the grill. Done. Will take you about an hour. Absolutely no need for a mechanic what so ever. If you are careful you can do it yourself. Just remember to connect it to the condenser only not through both the condenser and radiator.
Sounds to me like your timing chain is worn da frick out. Probably your camshaft as well.. Not only that, sounds like you need a rebuild of the stanadyne injection pump and a test of the injectors. How many miles does your truck have? My diesel has 600k+ and it is getting to the same point as yours, but not nearly so bad. I can still do 70 with a 4000+ lb trailer in overdrive. A local place rebuilt our injection pump and told us the camshaft is worn out about 50,000 miles ago... He advanced the injection timing to make it run worth a crap.
The only time I've experienced such a dramatic loss of power such as yours is when the injection pump was about to bail on me. It's gone three times in the life of the truck. The first time, we had no idear what was going on.. I haven't tried my hand at rebuilding the pump yet, but supposedly there's some "elastomeric bearing" inside the pump that just gets ett up after time. I think the better quality of diesel fuel you run through the engine, the longer that bearing lasts. 150k - 200k seems to be the "normal lifespan" running on diesel in southern VA.
I just did a search for 6.2 timing set.... i found a nice page.... They have a gear drive for the diesel... it's straight-cut, so it will be noisy, but it's better than a chain... I just installed one on my mustang.. makes a nice whine, but could be annoying to you (although, the diesel makes a lot more noise than a cleveland),.... an angle-cut timing set would offer the same advantages but would also be quiet...
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They also have new Stanadyne pumps for a shitload better price than I was charged to have mine rebuilt and R&R'd last time.... yet another example of why i do my own automotive work.
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Don't mean to point out the obvious, but have you tried changing the fuel filters? The air filter?
7000lbs is a lot to tow with your Blazer. Spending the money for a tranny cooler would be the cheapest insurance you could buy (even if you had to pay someone to install it). When I installed mine on my 87 Blazer, (I tow a 3000 lb sailboat) I didn't like the idea of tieing it to the AC condenser per the instructions. I looked around my shop and found some 1/2 inch aluminum angle and fabbed up a pair of brackets to keep the cooler about 1 - 1 1/2 inches from the condenser. I did install the cooler in series with the factory cooler in the radiator, (per the instructions) but after reading what Gary the TranSurgeon had to say I will be changing it to just run through the aux cooler when the weather breaks. ( I parked it last fall to do a body restore and make it into more of a play truck). I puked the first transmission at around 97k miles (no aux cooler at the time). After paying $1200 bucks for a reman on my trans with a 24mo/24k warranty I didn't want to have to do it again. When I parked it it was showing 190k miles and still going strong towing through the finger lakes region of NYS. I Started towing with the wife's
97 Yukon last year and it does tow better (more ponies, longer wheel base better ride), and it has an aux tranny cooler. Just my $.02 JR
A 6.2 with 30k is still relatively new. With out the AC condenser you would just zip tie it to the radiator and cut off the excess zip tie. Also means you don't need to remove the radiator shroud so, should knock 15 min off the instillation process. The down side when you do have to replace the radiator you will have to get 4 new zip ties from the autoparts store. No other problems. Save the old injection pump but that is not your issue. When the injection pump goes bad it will smoke a lot and eventually not start any more. If the injectors go bad it will just smoke a lot and get bad economy, also not your issue. I really think you can solve the problem with a high flow thermostat and a trans cooler. Both you can do yourself in a few hours. Just be careful to completely clean the thermostat mounting surfaces, these are all cast aluminum and that cross over piece will cost you ~$150 to replace (cracked one once, was not happy).
Look for a set of non turbo exhaust manifolds for a 6.5. The 6.2 manifolds have a cast in restrictor ring in them just above the exhaust pipe mounting flange. The 6.5 doesn't have that. They are hard to find, but they are out there, I found a set and put them on my 84 Sub. Then 6 inches down stream I went to 3 inch pipe from each side to dual MagnaFlow mufflers with 3 inch to the backend. It was loud, but I picked up a noticeable amount of torque. Later had a crossover welded in at the muffler shop that took the crackle out of it.
someone told me a long time ago you won't get any more power out of the diesel by changing the exhaust without putting on some sort of forced induction or upgraded fuel system.. something about the airflow not changing due to no ait throttle.. dunno guess that person was wrong huh?
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