Red1978
New Member
New to the site but have owned my 6.5 TD for 2 yrs now. Was having trouble putting in truck info in my profile so it's at the bottom of my post.
I recently noticed on a trip about two weeks ago where I was hauling a trailer full of equipment from Baltimore to North Carolina and back that my low coolant light came on when I was driving back. I hadn't noticed any leaks and only one time climbing a very long stretch coming into the mountains in North Carolina did the temp gauge ever climb up past 200. The truck ran fine for the entire trip. When I got home I topped off the reservoir but was wondering why I lost some coolant but it wasn't a lot to top it off. A couple days later I noticed the low coolant light coming on and going off and figured I needed to check for a leak. I stopped at the post office and while I was walking back to the truck noticed a small drip under the truck which was coolant. I opened the hood and noticed that the fitting that connects from the thermostat housing (left side of thermostat looking towards cab) to the line that runs into the heater core (behind the firewall) was slowly dripping. I grabbed a large c-wrench and went to tighten it hoping that the drip would stop and the threaded end of the fitting just snapped causing some coolant to dump out of the system. I grabbed some vice grips to spin out the threaded end connected to the thermostat and the threaded section of the fitting just snapped. I tried breaking it out with a deadblow and a screwdriver but to no success.
At this point the line to the heater core was fine and the thermostat was fine except the threads from the fitting being stuck inside of the connection point. Being stuck in a parking lot I tried to Magyver a fix just to get it home. I initially tried to knock out the threads stuck in the thermostat housing to no success. I then tried to file it down with a small round file to attempt to mate the line (no fitting) and the thermostat housing and e-tape/gaff tape enough to get home knowing I would need to most likely top it off and stop to top it off because it wouldn't be a tight seal but enough to get me home (30 min driving maybe). I couldn't get enough of the threads out so getting the line inside of thermostat housing wasn't going to work and there's a ac line and not enough room to work with. So I took the fitting (minus threaded end which had broken) and filed down the end flat. I did the same on the thermostat housing end and mated them together and covered/sealed with some quick steel epoxy putty. I topped off the reservoir with coolant a little high but figured that since I lost some of the coolant from the upper radiator section into the thermostat it would even out when I started the engine because the engine was off when I lost the coolant and at no time was/has the temp gauge been above normal operating temp.
Initially the fix did exactly what I thought it would do which was it only dripped slightly when I started the engine and I would be able to get home. I left the engine running for a few min just incase. When the pressure built up in the system it started spraying from my fix and then somewhere else it started dumping coolant from under the back of the engine. Of course I shut it off when I saw that. I gave up and had it towed home at that point. I checked the dip stick and no milkshake of coolant in the oil pan so the head gasket is fine. I'm stumped on where else the coolant could leak from. It doesn't appear to be from the lower radiator hose or the inlet or outlet from the heater core. I'm not sure if I managed to get any very small metal shavings in the system when I was filing down the threads.
Now here is my secondary problem. GM doesn't make the single thermostat any more and I can't find a single through Rock Auto or any of the other parts stores. I've already tried one of the local junk yards but that's a needle in a haystack. I've got a couple of options which are to buy a single thermostat housing from someone off of a 6.5 or to upgrade to a dual thermostat set up since I can't get a single.
Does anyone know which other years besides the 96' single thermostat will work? I know 96' is a cut off year.
I don't know if there's an FAQ on the single to dual conversion I haven't found yet but aside from physically putting a dual thermostat in place of the single are there any other changes I have to make? Do I need to replace the water pump as well?
Is there a high output single thermostat set up I can find as an aftermarket through SS Diesel or Kennedy?
Looking for advice on where to check next for the big leak that occurred after my Magyver fix and if I can't find a single thermostat housing (prefered) about doing the conversion so I can fix the initial thermostat/line problem.
Thanks. Truck will sit sadly until then.
1996 6.5 TD K2500 HD extended cab long bed F vin
Relocated PMD
Replaced harmonic balancer and front main seal
New front calipers, wheel hub, rotor, pads, flexible brake lines
New upper balljoints, control arm bushings, tie rods, axles
New rear brake shoes
New steering stabilizer
9 blade fan upgrade and cooling system flush
Single Thermostat
2 new batteries
New stock alternator
New Bosch glow plugs
I recently noticed on a trip about two weeks ago where I was hauling a trailer full of equipment from Baltimore to North Carolina and back that my low coolant light came on when I was driving back. I hadn't noticed any leaks and only one time climbing a very long stretch coming into the mountains in North Carolina did the temp gauge ever climb up past 200. The truck ran fine for the entire trip. When I got home I topped off the reservoir but was wondering why I lost some coolant but it wasn't a lot to top it off. A couple days later I noticed the low coolant light coming on and going off and figured I needed to check for a leak. I stopped at the post office and while I was walking back to the truck noticed a small drip under the truck which was coolant. I opened the hood and noticed that the fitting that connects from the thermostat housing (left side of thermostat looking towards cab) to the line that runs into the heater core (behind the firewall) was slowly dripping. I grabbed a large c-wrench and went to tighten it hoping that the drip would stop and the threaded end of the fitting just snapped causing some coolant to dump out of the system. I grabbed some vice grips to spin out the threaded end connected to the thermostat and the threaded section of the fitting just snapped. I tried breaking it out with a deadblow and a screwdriver but to no success.
At this point the line to the heater core was fine and the thermostat was fine except the threads from the fitting being stuck inside of the connection point. Being stuck in a parking lot I tried to Magyver a fix just to get it home. I initially tried to knock out the threads stuck in the thermostat housing to no success. I then tried to file it down with a small round file to attempt to mate the line (no fitting) and the thermostat housing and e-tape/gaff tape enough to get home knowing I would need to most likely top it off and stop to top it off because it wouldn't be a tight seal but enough to get me home (30 min driving maybe). I couldn't get enough of the threads out so getting the line inside of thermostat housing wasn't going to work and there's a ac line and not enough room to work with. So I took the fitting (minus threaded end which had broken) and filed down the end flat. I did the same on the thermostat housing end and mated them together and covered/sealed with some quick steel epoxy putty. I topped off the reservoir with coolant a little high but figured that since I lost some of the coolant from the upper radiator section into the thermostat it would even out when I started the engine because the engine was off when I lost the coolant and at no time was/has the temp gauge been above normal operating temp.
Initially the fix did exactly what I thought it would do which was it only dripped slightly when I started the engine and I would be able to get home. I left the engine running for a few min just incase. When the pressure built up in the system it started spraying from my fix and then somewhere else it started dumping coolant from under the back of the engine. Of course I shut it off when I saw that. I gave up and had it towed home at that point. I checked the dip stick and no milkshake of coolant in the oil pan so the head gasket is fine. I'm stumped on where else the coolant could leak from. It doesn't appear to be from the lower radiator hose or the inlet or outlet from the heater core. I'm not sure if I managed to get any very small metal shavings in the system when I was filing down the threads.
Now here is my secondary problem. GM doesn't make the single thermostat any more and I can't find a single through Rock Auto or any of the other parts stores. I've already tried one of the local junk yards but that's a needle in a haystack. I've got a couple of options which are to buy a single thermostat housing from someone off of a 6.5 or to upgrade to a dual thermostat set up since I can't get a single.
Does anyone know which other years besides the 96' single thermostat will work? I know 96' is a cut off year.
I don't know if there's an FAQ on the single to dual conversion I haven't found yet but aside from physically putting a dual thermostat in place of the single are there any other changes I have to make? Do I need to replace the water pump as well?
Is there a high output single thermostat set up I can find as an aftermarket through SS Diesel or Kennedy?
Looking for advice on where to check next for the big leak that occurred after my Magyver fix and if I can't find a single thermostat housing (prefered) about doing the conversion so I can fix the initial thermostat/line problem.
Thanks. Truck will sit sadly until then.
1996 6.5 TD K2500 HD extended cab long bed F vin
Relocated PMD
Replaced harmonic balancer and front main seal
New front calipers, wheel hub, rotor, pads, flexible brake lines
New upper balljoints, control arm bushings, tie rods, axles
New rear brake shoes
New steering stabilizer
9 blade fan upgrade and cooling system flush
Single Thermostat
2 new batteries
New stock alternator
New Bosch glow plugs
