Cold turbo!

[brokedown]

So my bus has the T444E and overall it runs great... But it does have an annoying thing it does.

When its cold out (Florida cold, so we're talking like 40s or below), the turbo don't wanna work. It's clearly disengaged, presumably by a temperature sensor that decides it should warm up a bit before spinning at a bazillion RPM. The problem is, as it warms up, it still doesn't kick in. The fix is to reboot the bus. I've even tested just flipping the key to off and right back to run while driving down the road and that's enough to fix it.

So when the turbo is "offline", the bus runs bad. No power, black smoke out the back, loud whooshing noise as air is directed through something it normally isn't.. Pretty rude to be driving around. I don't have an issue with idling for a few minutes to warm things up, but this falls into the "that's not right" category and I'd rather try to fix it than ignore it. I was pretty safely able to ignore it for a while since we were crossing triple digit temperature areas for the last several weeks, but we're in the SF bay now and it did it this morning.

I've done some googling and came up empty... Any thoughts?

[Brad_SwiftFur]

I have the same engine (except 2001 year model). The turbo shouldn't have any controls except one, the "turbo actuator". I can think of 3 possibilities going on here.

1: The actuator itself isn't working when it's cold.
2: The other gadgets that make the actuator work aren't doing their job (the most likely scenario here).
3. The turbo itself is sticking (given the description, I see this as unlikely but you never know).

The actuator itself apparently has a rebuild kit available and from a quick Google search there is a TSI for this part (04-12-19)
Part # 1833815C93 for model years 1998 and up (engine serial number; 661895 and later)
Part # 1833816C93 for model years 1994-97 (engine serial number; 500 through 661894)

From a little more reading around the inter-webs, seems some of these engines have a back-pressure system which basically helps them warm up quicker in cold weather areas and this is a potential failure point. Check the actuator (and the "arm" that connects it to the gate inside the turbo); apparently this can also be set up as an engine brake for anyone caring to do the mod.

Hope this helps.

[brokedown]

Indeed that gave me a few things to look into. It's surprisingly hard to find that TSB online, I still haven't found a source where I can read it for free But I did see someone else did a manual override on it to keep the turbo always engaged, which may be what I end up doing...

[Brad_SwiftFur]

Just give your local IH dealer a call and mention the TSI number; they should be able to pull it up and read it off and/or print a copy. That's what I do.

[cadillackid]

I thought some of these have an Exhaust backpressure valve.. that is there to help the engine warm up... it basically creates more exhasust backpressure and less turbo.. makes the engoine work harder and warm up faster....

if your bus was built and sold in the north it will have it... mine from Texas doesnt have it..
-Christopher

[cadillackid]

does your bus have the round deutsch style diagnostic connector? if so i can probably jump in with my computer and turn the thing off next time i see you..

my bus doesnt have the system and when it was 0f outside I still warmed up nicely and had plenty of heat..

rebooting the bus shuts it off because i believe it is built to run for so long if the coolant temp is below a threshold when you start it.. I'll have to look through the navistar books to see what the trigger point is and how long it stays on.. it does eventually shut off on its own.. probably coolant temp 140 or 160 is my guess..

which in your case if your Tstat is bad it might never make the shut off temp until you pull hard on the highway.. but that doing a key cycle - your engine is above the threshold where it would activate the system so it runs without it.

-Christopher

[brokedown]

I do have the deutch connector under the dashboard. Probably won't see you for quite some time but this isn't a critical issue just something annoying that only matters in cooler climates.

BTW it's beautiful in Berkeley right now! 70s during the day and a light breeze. Great bus weather.