Tranny or tach problem

[nums]

I'm confused and hope someone can advise.

I drove my 345 with 454 this weekend on a 4 hour trip.

Normally, she likes to run about 65mph while the engine is around 3,000 rpm.

Well, this trip I got up to cruising speed (65mph), and I see 4,000 rpm.

Odd that I didn't hear the noise because my dim recollection is that it gets significantly louder when going to 4,000. Instead, it sounded like 3,000 rpm.

Next thought, maybe my transmission is slipping the clutch. I pull off, drive at different speeds, etc. I note firm shifts in all 3 gears. Gas on/off with good response. Seems to not be slipping.

I drove for 4 hours this way. Temp pegged at 200 as normal

When I pulled over and shifted to neutral and park. Tach showed 2-2.2k rpm. High rpm on tach but didn't sound high.

I'm guessing that I've got some problem in my tachometer, but don't want to get my hopes up as the alternative is tranny work (ugh!).

[overlander63]

Yes, sounds like you need a new

[overlander63]

Tach.
My tablet did something weird, and I had to go find a computer to post the last word...

[mayco]

You would definitely hear the difference in the motor between running at 3000 vs 4000. That is, if youve driven your rig running at 3000rpm for any length of time in the past. Heres hoping and thinking its your tach.

[bkahler]

Here is a listing on ebay for a Teleflex speedometer & tachometer. The speedometer is a boat speedometer so not useable in your motorhome but the tachometer should be a direct replacement for your existing tach. That is assuming your coach has the black and orange Teleflex gauges like the 86 and earlier coaches do.

It could also be a loose wire somewhere between the tach and the ignition coil.

Brd

[TomKirk]

Before doing anything, confirm your concern with a manual tachometer.

- Nothing beats old school.

Tom