Canadian Hummer Club Forums

Well I traced a tranny fluid loss to the vampire issue with the cooling loop in the T-Case. I have bypassed it and flushed all hubs etc. There was even a mess in the air filter also.



I did not think the tranny got too low on fluid, no more than a quart or less before I figured it out, but now it seems I have a serious tranny problem. It shifts like crap between 1st, 2nd and 3rd when in town. Under harder acceleration it doesn`t do this. So I am going to play around with it to see how bad the damage is on Tuesday. Does anyone on here know of a good trustworthy tranny shop? Just in case I have to do a rebuild or service work. I plan on removing the damn thing myself, and getting the torque converter looked at also.

keep us updated.. hard luck...

I know a great tranny place but its in Brantford.

its darcy had mine rebuilt here in cambridge

transmission technologies

hes on eagle oand veru reputable

around 2600$ with custom torque converter so yours should be cheaper

if you need a hand let me know i have a shop

Check on the warranty if you install. May not have one , or limited.



So what made the cooling lines leak?? Loose t-case chain??

] he warranties if you drop off its a 4l80e tranny not much can go wrong unlike the older turbos with the shift linkage line

Well gents just an update.



I have solved the tranny problem and in fact it was not the tranny at all. After reading the info on the HML I traced the issue down to an electrical control issue. Once I utilized a scan gauge I found an electrical sensor fault code. It turned out that the DARC computer was providing intermitent info and causing the computer to send faulty signals. I just disconected it and was able to drive with harder shifts for a few days but no slipping. I was going to order a new computer from the dealer but they wanted like $400. So I went to the wreckers and looked in every Chevy truck that could have a 4l80e until I found a controller and unplugged it... $20 later all I had to do was reconfigure the jumper wires to match my old one and ensure the correct end drive ratio... Now I can pull the boat no problem and this was the cheapest fix on the Hummer I have ever had to date. WHEW!

[quote][/quote]So what made the cooling lines leak?? Loose t-case chain??





For those of you who are not aware, the Hummers have a huge issue with the cooling loop that is within the Tcase. Basically the setup from the factory utilizes tranny fluid to cool the Tcase through an internal loop within the Tcase. Well this loop is a piece of crap and often develops a leak. The leak is internal and the only symptom is the loss of tranny fluid as it is pumped into the Tcase and begins to quickly overfill it, once that happens it works its way up the vent lines and into the hubs and air cleaner. They call it the vampire because it sucks the transmission of its vital fluid and can easily result in tranny failure. AM General did a campaign to attempt to repair the issue, but the new ones have been known to crack also. The only fix is to replace the Tcase cooler loop which required the Tcase to be split in half or just say &^%$ it and bypass the coolant hoses like most other owners with this issue have done without any adverse effects. The H1 is the only known 4X4 with a cooling loop in the Tcase. The level of cooling that this loop provides is minimal and to counteract the issue of bypassing the cooling loop, just change the Tcase fluid more often.... its cheap anyways, just ATF fluid, use synthetic for better longevity with the higher heat.



It is actually a good thing my tranny DARC computer was causing problems as I don't think the vampire would have been found in time otherwise. It was only due to the slipping caused by the computer that I found the fluid getting lower and was able to deal with it. I check it often but once I realized there was a slow leak in the tranny fluid it became much faster very quickly and I would not have had any slipping until the tranny was so low that it was causing internal damage.