• Welcome to The Truck Stop! We see you haven't REGISTERED yet.

    Your truck knowledge is missing!
    • Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
    • We have tons of knowledge here for your diesel truck!
    • Post your own topics and reply to existing threads to help others out!
    • NO ADS! The site is fully functional and ad free!
    CLICK HERE TO REGISTER!

    Problems registering? Click here to contact us!

    Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!

What did you do with your GMT400 today...or yesterday....

dbrannon79 said:
I am curious on this dual x-over housing. I have the 95 single setup on mine with the HO pump. I have noticed that when I'm on the freeway my temp will get up to a 200 and the EV fan will turn on, cool everything off and then cycle off again. I have a 180 stat installed. when in town it rarley turns the ev fan clutch on except for when the AC is on. it never overheats or goes any higher than 200 ( where I have the fan controller set at. And I run empty 90% of the time.

@Husker6.5 you have me curious if the dual x-over will help with this.
Click to expand...

When we had the ‘95 Suburban at the time the advice was to go to the dual t-stat cross over, which we did, in addition to HO pump. It made a significant difference. Then everyone decided the single cross over was better, so we left that on the ‘94, while doing the rest of the cooling upgrades. Now everyone says the single unicorn crossover is the best, but you can’t get that one, so just keep dreaming about the unicorn cross over while your truck runs hot with no solutions after you’ve done everything the internet posting experts have said to do. I think that summarizes it.
 
Big T said:
When we had the ‘95 Suburban at the time the advice was to go to the dual t-stat cross over, which we did, in addition to HO pump. It made a significant difference. Then everyone decided the single cross over was better, so we left that on the ‘94, while doing the rest of the cooling upgrades. Now everyone says the single unicorn crossover is the best, but you can’t get that one, so just keep dreaming about the unicorn cross over while your truck runs hot with no solutions after you’ve done everything the internet posting experts have said to do. I think that summarizes it.
Click to expand...
if you do swap to the dual on your son's 94, let me know the outcome. I may want to attempt to source one for mine to try out. this might be the missing piece to the puzzle for the high flow upgrades. since there are apparently different styles. post a pic of the one you use and if you know what year it came from so I can look around for one similar.
 
The 130gpm pump (both the early design and the later balanced flow) and the dual thermostat crossover were engineered to work TOGETHER to flow more coolant and thus carry more heat away from the engine to the radiator to be shed!

The "single is better than dual" is an argument of apples to oranges of which is better to warm up the engine to operating temperature, NOT which one flows better! This "better" argument is due to the single having the bypass blockoff feature that recirculates coolant back into the engine to warm the engine up faster until the thermostat opens which the factory dual doesn't, which has been "fixed" with the dual thermostat by several aftermarket vendors.

For MAXIMUM coolant flow with the 130gpm water pump you MUST use the higher flowing dual thermostat crossover it was designed to work with! The ONLY exception would be to use the rare, transition design 96 LARGE stat single stat crossover.


Think of it this way. You just pulled the original straight 6 out of your 67 Chevy Nova and dropped a built 383 stroker into it. Would you still run the 383 into the original factory 1½" single exhaust pipe that the 6 used, or would you put on a 2¼" dual exhaust system so that 383 could breathe freely? Same thing with running the 94-95 single stat crossover with a 130gpm water pump. You're choking the pump down and not getting maximum performance from the pump's ability to move more coolant and thus remove more heat from the engine and take it to the radiator to be shed.

@dbrannon79 yes it would. Around town you're not producing as many BTUs of HEAT (do not confuse with temperature) from your engine because you're idling at stoplights, and are generally running at lower rpms overall at 35-40 around town in stop and go, than when running out on the hiway at a continual 2400rpm for longer periods and producing way more HEAT in the engine than the choked down flow of coolant can remove from the engine and take to the radiator to have the heat removed.
 
Not on my truck, but I finally started to dismantle the old VW Jetta diesel pulling the transmission out! it's been sitting as a yard ornament for long enough. and my youngest son just passed his written portion of his drivers ed online class... lol it's permit time
 
dbrannon79 said:
Not on my truck, but I finally started to dismantle the old VW Jetta diesel pulling the transmission out! it's been sitting as a yard ornament for long enough. and my youngest son just passed his written portion of his drivers ed online class... lol it's permit time
Click to expand...
At the risk of getting kinda far off topic, what year is this Jetta?
 
dbrannon79 said:
2006 Jetta 1.9l turbo diesel
Click to expand...
Oh, I would hardly classify that as old haha, I was thinking 80’s-90’s. That would be a BRM then. Well, make sure to run proper engine oil that meets VW spec in that puppy, they’re picky about that. And timing belt (of course) and cam wear are the other TDI killers, much like our old GM diesels, those TDI’s are great when they’re running, but they need love and maintenance lol.

(Ha now I just checked your signature, should have looked there first lol. Also those DSG trannys are neat)
 
Just my personal experiences here. Not trying to prove anything or make any claims as to what works best.

I run a 130gpm pump with a 190 GM thermostat. I start my truck 5-6 minutes before I leave for work (even in summer). I climb a mountain 1 mile from home and usually am moving pretty good up over it. I believe in warming up an IDI slow, and cooling it down fast (I never shut it down until egt is at 300, as opposed to shutting it down hot where the heat is trapped in the heads). Temp climbs to about 185 (indicated) before the stat opens, temp drops to about 130, and then climbs back to 160-170, and it will vary about 10-15 deg regardless of my driving.
I towed 10k up a mountain 2 weeks ago and the temp climbed to 190ish (one full line below 210) while I kept egt below 1100 with my foot (no water/meth). Yesterday, I towed 14k up the same mountain (water/meth on, flat to the floor for about 1 mile, before backing off slightly to hold an indicated 45mph in 2nd gear up to the top. Egt at 1100, water temp at 190 with gcvw over 20k. 15psi boost out of a modified hx35 if you're curious.
New 2 core radiator (.75" tubes), dmax fan, Hayden severe duty clutch (tuned by me), all underhood sound deadening removed, big Mishimoto cac under the front.

Maybe I have a freak. But this is what I have, and it works well.
 
J_dude said:
Oh, I would hardly classify that as old haha, I was thinking 80’s-90’s. That would be a BRM then. Well, make sure to run proper engine oil that meets VW spec in that puppy, they’re picky about that. And timing belt (of course) and cam wear are the other TDI killers, much like our old GM diesels, those TDI’s are great when they’re running, but they need love and maintenance lol.

(Ha now I just checked your signature, should have looked there first lol. Also those DSG trannys are neat)
Click to expand...
Yeah I did do a lot of research on the cam wear and what oils can be used. I found that the Rotella T-6 has enough ZDDP in the oil for this engine. it's not on the recommended list of oils but several have used it (reading in other forums) I have not seen any issues yet!

the DSG trannys seem to be a good manual over automatic shift, but fluid change intervals come too quick! VW wants it changed every 40k miles!!
 
dbrannon79 said:
Yeah I did do a lot of research on the cam wear and what oils can be used. I found that the Rotella T-6 has enough ZDDP in the oil for this engine. it's not on the recommended list of oils but several have used it (reading in other forums) I have not seen any issues yet!

the DSG trannys seem to be a good manual over automatic shift, but fluid change intervals come too quick! VW wants it changed every 40k miles!!
Click to expand...
Yeah T-6 doesn’t list the right VW spec but it meets the same API ratings or something, I know lots of TDI guys use it.
I would really recommend the TDIclub forum if you aren’t already a member, tons of info and smart people over there.
 
J_dude said:
Yeah T-6 doesn’t list the right VW spec but it meets the same API ratings or something, I know lots of TDI guys use it.
I would really recommend the TDIclub forum if you aren’t already a member, tons of info and smart people over there.
Click to expand...
I am a member there, just don't post much lol there is lots of good info on the tdi's there
 
Well a sad afternoon. just finished pulling the trans from the Jetta. found the input shaft splines are sheared off clean. so are the splines on the flywheel. it pulls out same as a manual trans so there are no bolts to a converter.
 
Gutted my intake plenum today and made a blockoff plate for the EGR, then tapped my boost gauge into the blockoff plate so I didn’t have to drill and tap in the intake plenum. Hooking up my boost gauge confirmed what I’ve been suspecting, I’m getting very little boost, like under 5psi, which I kinda knew because I haven’t been hearing any whistle for a while. So, now I get to make a turbomaster...
 
J_dude said:
Gutted my intake plenum today and made a blockoff plate for the EGR, then tapped my boost gauge into the blockoff plate so I didn’t have to drill and tap in the intake plenum. Hooking up my boost gauge confirmed what I’ve been suspecting, I’m getting very little boost, like under 5psi, which I kinda knew because I haven’t been hearing any whistle for a while. So, now I get to make a turbomaster...
Click to expand...
Check your vacuum pump and lines from it to the solenoid on the drivers side of the intake, then to the actuator on the turbo. it may be a simple cracked vacuum line. with everything connected and the engine idling you should not be able to move the actuator linkage by hand.

if all checks out then you might have one of three things failing. most common is the solenoid the vacuum lines are connected to. the other two are the MAP sensor on the intake plenum or the baro sensor mounted on the firewall up by the master cylinder, it won't have any hoses on it since it only reads atmospheric pressure.

the most common issues on these trucks to fail are the solenoid and the vacuum pump. if you do eliminate the pump and hoses for a turbomaster. you want to make sure you keep boost pressures under 12 psi for a stock engine without head studs. you will also likely get a check engine light since the PCM can no longer control the turbo actuator. at that point there are mods to "fool" the MAP sensor.
 
dbrannon79 said:
on mine, I found the main line coming off the rear of the vacuum pump had deteriorated and was collapsing. replacing that hose (iirc it was a 3/8" hose) fixed my no boost issue.
Click to expand...
Yeah I’m not really looking to fix the vac system, not really worth it on this truck, and the only thing it’s controlling is the turbo anyway. Such a complicated system for such a simple task. I’m considering deleting the vac pump as well.
 
If you are sticking with a factory turbo, you will see a loss in mpg going turbo master vs vacuum. But imo, worth it. I too say the system is too elaborate and the cost of maintaining it eats up the small gain in mpg. If you are going with a proper size turbo then you ditch the vac system anyways.
 
Will L. said:
If you are sticking with a factory turbo, you will see a loss in mpg going turbo master vs vacuum. But imo, worth it. I too say the system is too elaborate and the cost of maintaining it eats up the small gain in mpg. If you are going with a proper size turbo then you ditch the vac system anyways.
Click to expand...
Yeah I’m really wishing I hadn’t sold my HX35 when I upgraded the Dodge to the HE351, was still a good turbo and it would’ve been perfect for this truck. Oh well, just gotta let pylons be pylons, as Ricky would say (Trailer Park Boys).
 
Also noticed yesterday the top of my fuel filter canister thing is wet with diesel... not really sure where it came from. Would that indicate it’s maybe time to do a fuel filter relocate? I remember reading about that upgrade last year or something. I have a CAT 2 micron filter and filter base I could use that was a spare for my Jetta.
 
You must log in or register to reply here.
Back
Top