That TSB says where the head should be stamped. I doubt anyone anyone at Cummins would know about it. Think Its been 20 years since this was a problem, maybe someone in a dealership who has been there forever can remember doing 1 of them. Your engine IS definitely a problem. You need to see if that T stat hole has been bored out before you go spending money and time on a heater core. In that TSB their saying "hey we have a problem with all these engines that causes their not to get hot" i would go with what an engineer got paid millions of dollars to locate that problem before i start shooting in the dark. :tu:

Did you tru flushing your system with some radiator flush, your core could be just plugged up with crap. Another thing is make sure the blend door is moving all the way open to give you heat, not sure about your truck but the 2nd gens work by a vacum actuator :c:

Whats your water temp?

or you could try this same Idea for the heater

http://ramchargercentral.com/images/.../suitcase1.jpg
(Figure 1)



This is what it looked like after I scraped some of it off . I just used my fingernails and scraped in a downward motion.
http://ramchargercentral.com/images/.../suitcase2.jpg
(Figure 2)



Another picture
http://ramchargercentral.com/images/.../suitcase3.jpg
(Figure 3)



All cleaned up. I used a vacuum cleaner to suck it all out. There is a spray that you can buy at any place they sell air conditioning parts that will really clean the evap. up.
http://ramchargercentral.com/images/.../suitcase4.jpg
(Figure 4)



This is what came out.
http://ramchargercentral.com/images/.../suitcase5.jpg
(Figure 5)



This is what was covering the evap.
http://ramchargercentral.com/images/.../suitcase6.jpg
(Figure 6)



Make a cover out of thin sheet metal or plastic. I used a piece 7x5x1/16. Run a bead of rtv around perimiter.
http://ramchargercentral.com/images/.../suitcase7.jpg
(Figure 7)



Use small sheet metal screws to attach it. Anybody can make one of these with common shop tools. I just scribed the marks for the holes and drilled them on a drill press. A good drill will do.
http://ramchargercentral.com/images/.../suitcase8.jpg
(Figure 8 )



Add a little masking tape
http://ramchargercentral.com/images/.../suitcase9.jpg
(Figure 9)



Add a little dupli-color flat black engine paint (because that what I had) and wal'la you're finished.
http://ramchargercentral.com/images/...suitcase10.jpg
(Figure 10)



This is the coolant bypass valve I got off of an 90 Daytona Turbo fwd Chrysler car. This will keep the hot water out of the heater core.
http://ramchargercentral.com/images/...suitcase11.jpg
(Figure 11)



This is the cyciing switch (81-86 only). I pulled the copper wire(capulary tube) out about 2. inches. Its the wire with the white grease on it. The more of the wire that is in the capulary tube the shorter the cycle.
http://ramchargercentral.com/images/...suitcase12.jpg
(Figure 12)



There is another switch (low pressure) on the left side It cuts the compressor off when it gets low on freon (81-86 only). Here is a picture of that switch. The one on the left is the stock dodge switch the one on the right is an adjustable one I got off of a mid 90's Hyundai. This switch will allow you to have some ajustment on the low side.
http://ramchargercentral.com/images/...suitcase13.jpg
(Figure 13)



This is a picture of the end results It pulls down to 45 degrees at idle sitting in the texas sun at 94 degrees . On the way to work tonight it pulled down to 40 degrees. My 2000 Blazer doesn't do any better than that.
http://ramchargercentral.com/images/...suitcase14.jpg
(Figure 14)

The cylinder head is not the problem if he had heat last winter. Pay attention people. :argh: Check ur temps first.

If the engine is not getting hot the heater wont be hot. Fixing the heater core wont make your engine warm up faster. What changed since last winter? a coolant flush and a T-stat.

Before you go to the end problem you need a starting point. Putting a heater core in it may be whats wrong but its not logical to start with. your saying you drove hundreds of miles and the engine didnt get hot, your looking at something in the engine. You made that drive with the A/C on thus no water would even be going to your heater, so we can rule that out from the no engine heat part.

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You could see if the t-stat you bout is the same part number as the one in the TSB. it states its the only one available, but the parts guy most likely thinks all 12 valves are the same and grabs one off the shelf. give him that number and see what happens.

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Thats actually a Mopar part number that supersedes to 83506401AA. Looks like there is 93 left in the US. Its not cheap though(around $100 depending on the dealership), so try Cummins first.

ok, I pulled off my T-stat housing, and I don't really understand the TSB about the head ream out deal. My T-stat fits snug in my T-stat housing. It doesn't slip inside the head. It's real snug, fits great, I pulled it out and I have the right 2 pin, jingle deal(180 degree). The other T-stat I guess is a 1 pin, slightly bigger round. I still got no heat, although I'm not quiet sure of my water temp, because my thermo deal is mysteriously broke, dam kids. Any other idear's, I don't even want to think about f'n with my heatercore.

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:w2:

you have access to a lazer thermometer?

I just got another, and my temp is 172-181 on the termostat housing. I still got no heat!!!:argh: Could it be that little vaccum deal on the heater hose??
I'm still confused about the TSB deal with the head. Is there a thread about heatercore replacement??

ok now that ya got one shoot your heater hoses if one is way hotter than the other thats a 99% sign that the heater core is plugged shoot the hose before and after that vacuum switch in the line if its hot on one side only that thing is stuck closed put a meet thermometer in your center air duct above the radio mine blows about 140-150 when running fan on high in the vent position with the temp selector to hot

do all the testing you can with that thermometer then once you have a clue where the problem is at then tear into it

:pca1:

If you do have to tear into it good luck I did one on the 90 this is what i used and it was a bitch.........

http://www.dieseltruckresource.com/d....html?t=248580

Thank you! I'm gona do it now! Dam, that heatercoreis gona suckkkkkkkkk,well, I'm praying I don't have to replace mine.