TH400 question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

76bonanza · 12-03-2005, 12:38 PM

In an effort to find this whining sound in my truck I think it is the tranny. When it is cold outside I get this high pitch whine after I start it for a few seconds like 45 or so sometimes longer if it is real cold then it stops then when I put it in drive it does it again for a short time. Does not do it all when warm. Wondering does the th400 use gears instead of belts because that is kind of what it sounds like maybe untill the tranny fluid warms up? Any thoughts on this subject would be welcomed.

Thanks

cdyblu · 12-03-2005, 03:49 PM

I don't know of any "belts" in any automatic transmissions, It sounds to me like you have a converter problem or front pump. First thing I'd try it a filter & fluid change.

76bonanza · 12-03-2005, 04:37 PM

I did the fluid and filter about 1 month ago was rebuit about 6 months ago Not really sure it is even the tranny or not, shifts great runs strong. Just that wierd sound and only when cold thought maybe the tranny fluid was just cold. like 20degs for so.

chuck1960 · 12-03-2005, 04:48 PM

you just have three converter bolts, you can remove these and push the conv. back then start it up and see if you still have the noise. this will eliminate the trans. have you checked your acc. drive belts, p.s., alt. a.c.?

jracca · 12-03-2005, 06:50 PM

I may just be an idiot but I had a sound that is like you described and thought it was coming from the transmission and it ended up being the support bearing on the driveshaft, you probably already looked but just in case you didn't and you have a support bearing you might want to check it

alf1096 · 12-04-2005, 01:24 PM

my th400 does the something similar. It whines for about 2-3 miles and then it quits but it does not do it while it is idling

409biscayne · 12-04-2005, 01:36 PM

Quote:

Originally Posted by alf1096

my th400 does the something similar. It whines for about 2-3 miles and then it quits but it does not do it while it is idling

I thought my t400 was whining , but it turned out to be the wife . Ha ha. My ps pump makes noise on cold start up . Hope you find your problem .

da-burb · 12-04-2005, 07:38 PM

My guess to your problem is a trapped air bubble. I had this same sound from my th400. My solution turned out to be a good tranny additive. I think it was Sea Foam tranny conditioner. The sound went away shortly after adding the conditioner.

Lemield · 12-05-2005, 11:56 AM

I had the same noises in my C20 and a filter change fixed it. Good luck!

76bonanza · 12-05-2005, 01:06 PM

So what exactly is the difference between the th350 and th400 I thought one had bands and one had gears?

12-03-2005, 12:38 PM	#1
76bonanza Senior Member Join Date: Mar 2003 Location: St robert Mo Posts: 2,001	TH400 question In an effort to find this whining sound in my truck I think it is the tranny. When it is cold outside I get this high pitch whine after I start it for a few seconds like 45 or so sometimes longer if it is real cold then it stops then when I put it in drive it does it again for a short time. Does not do it all when warm. Wondering does the th400 use gears instead of belts because that is kind of what it sounds like maybe untill the tranny fluid warms up? Any thoughts on this subject would be welcomed. Thanks __________________ 1968 c10 lowered 3" 4" 355/Th400 built by Hatfield racing in joplin MO

12-03-2005, 03:49 PM	#2
cdyblu Registered User Join Date: Dec 2004 Location: Green Bay, WI Posts: 44	Re: TH400 question I don't know of any "belts" in any automatic transmissions, It sounds to me like you have a converter problem or front pump. First thing I'd try it a filter & fluid change.

12-03-2005, 04:37 PM	#3
76bonanza Senior Member Join Date: Mar 2003 Location: St robert Mo Posts: 2,001	Re: TH400 question I did the fluid and filter about 1 month ago was rebuit about 6 months ago Not really sure it is even the tranny or not, shifts great runs strong. Just that wierd sound and only when cold thought maybe the tranny fluid was just cold. like 20degs for so. __________________ 1968 c10 lowered 3" 4" 355/Th400 built by Hatfield racing in joplin MO

12-03-2005, 04:48 PM	#4
chuck1960 Junior Member Join Date: Oct 2005 Location: cleveland, tn. Posts: 71	Re: TH400 question you just have three converter bolts, you can remove these and push the conv. back then start it up and see if you still have the noise. this will eliminate the trans. have you checked your acc. drive belts, p.s., alt. a.c.?

12-03-2005, 06:50 PM	#5
jracca Registered User Join Date: Oct 2005 Location: Dallas, TX Posts: 49	Re: TH400 question I may just be an idiot but I had a sound that is like you described and thought it was coming from the transmission and it ended up being the support bearing on the driveshaft, you probably already looked but just in case you didn't and you have a support bearing you might want to check it

12-04-2005, 01:24 PM	#6
alf1096 Registered User Join Date: Aug 2005 Location: Texas Posts: 124	Re: TH400 question my th400 does the something similar. It whines for about 2-3 miles and then it quits but it does not do it while it is idling __________________ 1970 Short Stepside----Process of Restoring 1983 1/2 Silverado

12-04-2005, 07:38 PM	#8
da-burb "Ochre Ogre" Join Date: Apr 2000 Location: Springfield, MN Posts: 3,558	Re: TH400 question My guess to your problem is a trapped air bubble. I had this same sound from my th400. My solution turned out to be a good tranny additive. I think it was Sea Foam tranny conditioner. The sound went away shortly after adding the conditioner. __________________ Bowtie Truck Stop Inc. Mid-West GM Truck Restoration Parts Supplier Your Key Parts, Auto Metal Direct, Dynacorn, and Goodmark dealer. like us @ www.facebook.com/BowtieTruckStop 1971 C-10 Suburban (Ochre) 1971 K-10 Suburban (Ochre) 1972 C-10 Suburban (Ochre) 1972 K-20 Suburban (Yellow- that just aint right!) Springfield, Minnesota 56087

12-05-2005, 11:56 AM	#9
Lemield Registered User Join Date: Dec 2004 Location: Arvada Colorado Posts: 1,321	Re: TH400 question I had the same noises in my C20 and a filter change fixed it. Good luck! __________________ Larry 1949 Willys CJ2A, Kubota Turbo Diesel engine, Warn Overdrive, 11 inch brakes, 12volt, Warn M8000 Winch "Little Green" 1970 Rustoleum Roller Red C20 Custom Camper 454 TH400 "Big Red" 1971 K20 6.2 Turbo Diesel 4x4 4spd Ranger Overdrive "Pumpkin Wagon" 2005 VW Beetle Diesel 44+ MPG "Silver Bullet"

12-05-2005, 01:06 PM	#10
76bonanza Senior Member Join Date: Mar 2003 Location: St robert Mo Posts: 2,001	Re: TH400 question So what exactly is the difference between the th350 and th400 I thought one had bands and one had gears? __________________ 1968 c10 lowered 3" 4" 355/Th400 built by Hatfield racing in joplin MO

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