Weird sound at startup

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Chilly the last several nights here in the mtns of north Georgia. Didn’t seem cold enough to plug ‘er up, but this is my first season change with my truck, and I’m not sure what to expect.

So... I have a couple of mornings of crabby start-ups. It takes several tries, it bucks and bangs and loosens a few of my fillings, and then settles down. BUT--just after the engine settles down, I hear a rushing of water somewhere at or behind the firewall. No leaks anywhere; radiator still topped off. Is there a flush toilet hidden somewhere in this truck I don’t know about? Wasn’t on the option printout.

Any ideas?

P. S. I did change the heater hoses several weeks ago but had no problems until the past few days with the tough cranks.

Thanks.

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'95 2500 LB 2WD, auto, 66,000--Westech gauges, Prime-loc, Brite box, Back-off Box, Line X, Flowmaster muffler, Borgeson steering shaft

 

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Kodiak:

At the end of last winter my truck
made a similar noise that you
describe. I dismissed it as "just
normal noise" caused by the flow
of water through the system (i. e:
heater hoses, heater coil etc. )
However, about one month later
when the weather warmed up, I saw
water dripping down onto the carpet
on the passenger floorboard. As it
turned out, my evaporator coil for
the AC was bad! I ended up having
to replace it.

Now this MAY NOT be your problem
but check all your connections on
the cooling system, and I would
also check that evaporator coil
too.

Hope this helps!

------------
John_P.

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Red '96 4x4 2500 Auto 3. 54, TST #5, Pump Mods, Banks Exhaust, Prime Loc, Cummins Chrome Kit, Pro-Torque Converter, BD Valve Body, Sendel 16" Alum Wheels w/ 33" BFGs

 

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Kodiak,the defrost also turns on the AC to dry the air,that could also be what you're hearing. If you start it with the fan turned off it won't do it. Also with your hard starts,are you waiting for the wait to start light to go out before you crank it?I don't need to plug mine in until it gets below 20,as long as I wait to start it starts right up and runs great.

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95' 25004X4,AT,Driftwood,Banks,Warn fender flairs and running boards(Play truck)95 3500,5 speed,driftwood,Banks&phscotty,34,000 GCVW apple and tractor hauler(work truck)

 

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I agree with illflem. But if you are doing this then check out fuses,connections, grounds, wiring, heater relays both air and fuel,Intake manifold air heater, fuel heater.
Need to look at book or truck to see if cooolant can get thru heater hoses before thermostat opens.

 

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KODIAK

I believe the flushing water sound you hear is normal. My truck makes the same sound upon start-up everytime the engine block heater is used. I don't know why this happens. I suspect it has to do with where the block heater is located in the water jacket and maybe the heating element you hear "bubbling" away causes air to travel to the heater core and force the coolant out, then when the truck is started you hear the coolant flowing back into the heater core. This is only a guess on my part, dosn't make since though that air would be in the cooling system unless if it occurs from the engine block heating element boiling the coolant and causes air bubbles??? (kind of like how bubbles are formed when boiling a pot of water on the stove).

I have wondered for the past 5 years what causes the running water sound from the passenger side firewall when starting the truck after using the block heater, but I think it is normal.

 

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John_P - Thanks for the bit about the evap coil. AC has been a little less than enthusiastic lately. I’ll keep an eye on it.

illflem and Missourie Mule - Double checked on your suggestions--all seems well there.

1tuffram -- Your idea makes sense as it happened on the two times I was experimenting with the block heater.

**New info just in!** Took truck to DC dealer about paint issue (another story--another time--happy ending, though), and they couldn’t start it the next morning, either. Poked around and announced the dreaded rotten fuel lines. Also mentioned that the water-rushing sound could come from fuel when prime reestablishes itself.

I’m replacing the lines, I’ll keep you posted.

Thanks again for all your help.

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'95 2500 LB 2WD, auto, 66,000--Westech gauges, Prime-loc, Brite box, Back-off Box, Line X, Flowmaster muffler, Borgeson steering shaft

 

[Archive]

Kodiak:

I don't believe the dealer's diagnosis of the rushing-water sound coming from loosing fuel system prime. Ask them for a detailed explaination (it ought to be pretty entertaining!!!) I have never had a problem with fuel system prime and the only time I notice the water rushing sound is after the engine block heater has been plugged in for several hours.

Glad to hear they where able to figure out the hard starting problem.

That fuel return line can be a bugger to replace the first time.