Chevy C-5500 Kodiak Duramax potential safety issue!

[bob-kir]

I was recently returning home after spending the winter in Mexico in our 08 Seneca Duramax with 65,000 miles on it when I had an unexpected engine shut down!
I was driving about 63mph in the right lane in heavy traffic coming into St. Louis towing a car when a very loud continuous warning buzzer sounded and a couple of dash warning lights came on. I couldn’t tell what the icons on the warning lights represented but all of the gauges read normal. I was reducing my speed when the engine shut down, maybe 10 seconds after the alarm started sounding. Now I had no power steering or brakes. Luckily, I was right at the exit for a weigh station. I wrestled it over and got it stopped in the station truck parking area. Had to sit for a couple of minutes to calm down. It took considerable effort to just make the slight steering correction to enter the exit lane. Had I been on a curvy 2 lane road I don't know if you would be able to keep it on the road.
After stopping and checking the manual the warning lights indicated “low coolant” even though the dash temperature gauge was reading normal. I opened the hood and saw that the coolant reservoir was below the minimum level. Then I noticed coolant dripping from under the reservoir and saw that the hose that exists the bottom of the reservoir was about ready to fall off. It had slid down about 2 inches and was within a 1/4 inch of falling off completely. The clamp that holds it on is a steel compression ring with no way to tighten it. I slid the hose back to its original position and put on an additional hose clamp to secure it and added a gallon of water and we were go to go.
Before we leave Mexico I always do pretty thorough engine check , belts, hoses, fluid levels but never looked under the coolant reservoir to check the position of that hose. My guess is that the very rough Mexican roads were a factor in the hose coming loose.
I will always check that hose from now on!

[ronfisherman]

Information above is good no how Hydro Boost works. On GM Medium Duty Trucks there is a difference. A electric pump is used to provide boost when power steering pumps fails or engine is not running. Here is picture showing master cylinder and pump motor.

[FunTwoDrv]

Thanks Drew

Gary

[DrewE]

FunTwoDrv wrote:
Help me understand something... doesn't hydraboost utilize the hydraulic pressure from the power steering pump to "boost" the brake pedal? Is there actually an accumulator somewhere that holds some pressure to aid in braking once the engine is off?
Gary

Yes, and yes--it holds some pressure both in case of the engine shutting off and in case of the power steering pump or its drive belt failing. The accumulator is sometimes incorporated as a part of the hydroboost brake booster unit itself, rather than being a physically separate component. It only provides emergency pressure for the brakes, not for the steering power assist.

Here's some more general information, perhaps more than you really wanted, on the system.

[FunTwoDrv]

Help me understand something... doesn't hydraboost utilize the hydraulic pressure from the power steering pump to "boost" the brake pedal? Is there actually an accumulator somewhere that holds some pressure to aid in braking once the engine is off?
Gary

[ronfisherman]

I replaced the complete tank on my 04 and friends 05. It was only $40.
Not that price anymore. ACDelco 15161670 GM. Got it from Amazon. Did a quick check. Part # is good for 2003 to 2009.

[Latner]

Had this happen to a work truck, it would occasionally sound the alarms and die when taking a curve fast. Topping off the surge tank seemed to help until one day I could hardly drive the truck even with a full surge tank. I ended up replacing the sensor at the bottom of the surge tank, problem solved. You'll have to get the sensor from a dealer, the only place I could find it.

[Jaxom]

Good Luck. Keep us up to date if any further problems surface.

[bob-kir]

Hopefully, it was just low coolant. It’s run fine since and we drove through some heavy rain which should have rinsed off any coolant that was spilled.

[Grit_dog]

^ That. While I'm not familiar with the Kodiak chassis, vehicles are not programmed to die mid stream for virtually any fault or default.
But like anything, especially older vehicles, stuff happens and it is a potential safety issue, separate from an old coolant hose connection coming loose.

[carringb]

Unfortunately I don't think the engine shut-down was because of the low coolant level. It could however, have a new electrical issue because of the coolant leak.

My 2008 Topkick work truck did the same thing. About 10 seconds of warning noises, the it just shuts off. Completely. If only became became more and more regular, and eventually I got pretty good a rolling re-start. We took it to both Allison in Junction City and to DSU-GMC in Portland. It was an intermittent electrical issue, and we replaced the engine main harness, the PCM, the transmission harness and solenoid pack to no avail. We eventually ended up removing the body and scrapping the chassis. The downtime and potential liability was just too much.

I would definitely trace the path the coolant might have taken, and clean everything well with water and electrical cleaner. If I remember right, one of the chassis main harness runs below the bottle. Plus any harnesses downstream and aft inside the frame rail on that side, since coolant can blow a long ways. I'd even suggest pulling apart any downstream connectors. CRC makes a good spray cleaner for this kind of stuff.

[bob-kir]

Yes, the Hydroboost on my Seneca is working fine. It seemed as if it took more effort to stop but with the sound of the alarm going off, dash warning lights, the Hyroboost noise, the shut down engine and wrestling with the lack of power steering in heavy traffic, I could be wrong remembering the feel of the brakes. It was a relief to get it stopped quickly in a safe place!

[ronfisherman]

I had the same condition with my 2004 MH. Only difference was engine shut off after after I came to a stop. It happened on a busy exit ramp. I took a wire and shorted out connector to antifreeze tank level sensor to get engine running again.
As far as I know the brakes worked OK. Hydroboost should have kept brakes working as normal.Test it by pressing on brake pedal without engine running.

[opnspaces]

But it is scary that the engine shut off when the gauges read normal. It seems to be putting the safety of the engine above the safety of the people.

[ScottG]

bob-kir wrote:
It was a long straight run to the truck parking area so I didn’t apply the brakes vert hard. When I did use them the brake pedal felt mushy and it took more effort but they worked.

That's normal under those conditions. There's a small amount of "assist" stored in the accumulator for just that situation. It doesn't feel exactly the same but it gets the job done.