Thermostat housing on the back of the engine??

[n8in8or]

I must admit, I haven't done any research on this, so if I'm saying something stupid here I apologize.....

Last night before we ran off to get some stuff at a friend's house I showed my brother where I was with the installation of the mechanical pump and how I was having thermostat housing interference issues with the double thermostat housing. Things are really easy to see when you're working on a bare engine and the crazy idea came up of putting the housing on the back head ports instead of the front head ports. We said it jokingly at first then started to wonder if there was any validity at all. Sure it would take longer hoses, but that's no biggie. It could clean up the front of the engine and make the throttle bracketry much simpler, sure, but if the back cylinders are the ones that run hot, what if the coolant was pulled up from the back of the engine instead of the front??? I haven't seen how the cooling circuit works on a 6.2/6.5 to see if it's even feasible, but I know a few of you guys are way more knowledgable on this subject and may have some insight on this.

Even if someone thinks maybe it COULD be done, I'm not sure I would do it just for the sake of being a guinea pig. But I thought maybe it did warrant starting a conversation. Anybody know if it's been done? I know Heath was offering a crossover kit in the back and that was a bad idea, but that is a totally different scenario - and I totally get why that didn't work. But this idea.....hmmm, I don't know, maybe? It's a lot more open in the back of the engine, and Will L had mentioned using a remote thermostat, maybe this is the ticket to doing that?

 

[THEFERMANATOR]

Wouldn't work. The head gaskets main coolant ports to let coolant to pass from the block to the heads is at the rear. So your heads would overheat in the front from lack of flow. If you could somehow swap the head gaskets around, then the block would overheat.

 

[n8in8or]

Wouldn't work. The head gaskets main coolant ports to let coolant to pass from the block to the heads is at the rear. So your heads would overheat in the front from lack of flow. If you could somehow swap the head gaskets around, then the block would overheat.

I wondered if it would cause coolant flow to bypass certain parts of the engine, but thought I'd ask the question. Thanks for the response.

 

[JayTheCPA]

Maybe see what parts BobbieMartin has left from his DB2 conversion Burb?

http://www.thetruckstop.us/forum/threads/1995-suburban-with-optimizer-db2.45109/

 

[Will L.]

My remote tstat is going to plumb the same as factory routing. With van manifold, db2, and the tighter compartment of a hummer, I cannot fit the good single stat crossover. If you can use that single stack crossover the Bobby Martin has like Jay said...

I and others in Vegas experimenting with different set ups. Including dual-single thermostat crossovers, one front and one rear. (Failure). I have never seen anyone try moving the cross over to the rear of the engine and blocking off the front.

 

[n8in8or]

Maybe see what parts BobbieMartin has left from his DB2 conversion Burb?

http://www.thetruckstop.us/forum/threads/1995-suburban-with-optimizer-db2.45109/

Thanks Jay. Yeah I saw he was parting his out but thought I'd make parts fit my own way. I think I'm just going to go with the 96 single housing that I have in order to make mine work. I just thought I'd throw this idea out there in case it was new and solved some colling system problems. You never know if you never ask and sometimes stupid ideas turn into good ideas in another way when they're picked apart.

 

[Will L.]

I cannot remember the head gaskets blocking off the rear feed to the heads. Not disagreeing with Ferm-but I cannot picture it.

Ferm- What would happen if you were to open up the gasket in front and rear? Even if you kept the block off plates in place on the heads.

 

[WarWagon]

Generally coolant flows from the water pump into the front of the block. It then flows backwards and enters the cylinder heads in the rear of the block. Causing #7 and #8 to be running the hottest BTW. The coolant then flows through the heads from the back of the engine and out through the T-stat crossover. There are some other flow paths to split hairs, but, this is the general idea to illustrate why things are where they are. The hottest part is the heads and specifically the front of the heads where the temperature sender for the gauge is. Due to balance flow issues the hottest head is actually the passenger side and the temp probe is on the drive side.

Modern designs mix the hot coolant and cold radiator return coolant reducing cold shock and delivering a more even engine temperature.

Coolant boiling and the steady flow of water vapor out of the engine as lots of bubbles is not well understood. Old designs and lower temps worked well enough without this understanding. Specific example the LS2 engine and GM's reduction of the steam/air vents off the heads in some applications like the Trailblazer SS. If the radiator isn't below the boiling point of pure water at that pressure it's not going to condense back into the coolant mix. If the steam can't get out of the engine to the radiator you have problems like the "air purge" issues TrailBlazer SS's have - full of coolant after a change and the engine heats up because it won't burp the air or steam out of the engine. You literally have to pull a hose off the head's steam vent system to let it out. The major FUBAR is forcing steam to go "down" before it can reach the radiator - and additional FUBAR is how it's plumbed into the system rather than just going to a high spot on the radiator. Note the thermostat and other coolant parts are lower than the water pump on these engines.

 

[NVW]

Could the crossover be rotated 180* on the front of the heads and a fabbed rad hose be used? I can't visualize if it would fit up or if there would be clearance.

 

[n8in8or]

Could the crossover be rotated 180* on the front of the heads and a fabbed rad hose be used? I can't visualize if it would fit up or if there would be clearance.

It might physically bolt on but I'm pretty sure it will hit the accessories. It may hit the IP and intake too. I need to get an extra set of accessories for my mock up engine I think.

 

[Will L.]

It will hit. Chased that dog.

 

[NVW]

Spacers?

 

[Will L.]

No.
Then the "tubes" are too long. If the heads were flat then yes, but because of the v shape the spacer makes the bolting location closer together.

If your crossover won't fit, really get the one from Bobby. You know that one will fit and accept the correct thermostat. They are out there, but I haven't seen many for cheaper.

Mine won't because the van manifold is huge and in the way, vans never had a db2 and cruise control with these manifolds, only ds4, or a different manifold when db2. Then the clearance to my hood is less than 1". That's why I'm stuck. If I'm going to cut something up, I might as well start from scratch instead of chopping a part that's getting a little harder to find.

 

[WarWagon]

To clarify they confusion in my post above - coolant flow from front to rear of block - then into the heads at the rear - then from rear of heads to front t-stat crossover. The reverse of the coolant flow can be misread and was intended to say direction front to rear reverses as it goes through the heads.

 

[Burning oil]

Did you try flipping the neck like I did on mine? I posted the part # of the hose in your other thread.

 

[n8in8or]

Did you try flipping the neck like I did on mine? I posted the part # of the hose in your other thread.

No I haven't. I haven't had a chance to work on it since the other night. I'm pretty sure I'm going to use the 96 crossover the more I learn about the cooling system. I just started this thread to talk about the hypothetical idea of putting the thermostat crossover on the back of the engine. It turns out to be a bad idea, but I'm glad I asked.

 

[Burning oil]

If you get the single to work I'll copy what you do. I wanted to run the single but the neck is further to the right and got in the way of the IP bracket.
I flipped the dual and drilled/tapped a new air vent for it.

 

[Nosferatu49534]

I'm sure it's been said before but which cross over is better the dual or single? This is good info n8in8or. I plan on converting as well and all the info I can get and is out there on trial and error and questions the better.

 

[n8in8or]

I'm sure it's been said before but which cross over is better the dual or single? This is good info n8in8or. I plan on converting as well and all the info I can get and is out there on trial and error and questions the better.

Yeah it's been debated a lot. I've heard enough stuff from others I trust to convince me the single will be better.....or at least I won't be any worse off with the single. The one thing I definitely like with the single is that it blocks off the thermostat bypass when the thermostat is open. That in itself is a great feature. Also the point was brought up (I think in my mechanical conversion thread) that both the Ford and the Cummins diesel work fine with just a single thermostat. I looked up the Ford thermostat and it's the same basic size as our single thermostat, so I think that is sound information. It's nice having smart guys here that have already been there and done that to bounce ideas off of.

 

[WarWagon]

The other brands are in different aerodynamic bodies that have different ram air airflow through the stack. In other words they don't have to compensate so much for a lack of airflow through the radiator. Further their turbo designs and charge air coolers make a difference in the amount of heat trapped or dumped in the engine. IDI also makes more heat.

When GM went to the NBS in 1988 aka the 6.5's body style over the square body 6.2 they lost a lot of radiator airflow in the interest of aerodynamics and MPG. GM also FUBARED the "reverse rotation" change to the water pump from V-Belts and wound up with unbalanced coolant flow in the engine that would boil the passenger side head. Not only in 6.5 Diesels, but, in 350 gas engines. You could literally boil over a 1995 350 with the temp gauge reading "normal". The fix was to replace the water pump on the 350. Further trouble with the 6.5 is raising the fan clutch turn on temp - supposedly due to customer noise complaints from the fan. Regardless the 6 bolt 6 blade fan will overheat the clutch and kick out (fail) when you need it most.

So the main reason to go to the HO pump is balance flow and more flow on the hotter passenger side. Concerns for pushing out freeze plugs from a HO pump and single t-stat are one reason stated in a improvement guide. Simply put the single T-Stat can't flow enough to match the HO pump.

IMO the dual T-Stat isn't needed esp with the block off missing. Say optional here. (The missing block off will still allow more flow through the engine.) In your MI climate with more fuel IMO isn't as harsh as 121 degree AZ weather. That's all I have run is the single T-Stats. Getting the fan on when needed is a delay I fight the most.