Missing Tachometer

[tylermay209]

Hi everyone!

I took possession of my bus yesterday! After replacing all three batteries (talk about a hefty price - they took the $380 off the purchase price though ) the bus runs like a dream. You can see the stats in my tidbit under my avatar. The bus was extremely well taken care of, and was in service right up until this fall. Engine appears to have to rebuilt as well - everything under that hood is brand new.

However, on the ride home, I noticed something - the bus does not have a tachometer! I'd like to purchase an original one to match the rest of the cluster, but I imagine I'm going to have a hard time locating one due to the age of the bus. Is this common for school buses?

[PNW_Steve]

Congrats on the new bus.

It is not unusual for buses that have no tachometer from the factory..

Tell us about your bus? There are different options for adding a tach depending on year, engine and type of bus.

[tylermay209]

Originally Posted by PNW_Steve

Congrats on the new bus.

It is not unusual for buses that have no tachometer from the factory..

Tell us about your bus? There are different options for adding a tach depending on year, engine and type of bus.

Some specifications on my bus:

1989 Carpenter S/1753 International
International IDI 7.3L Diesel
Allison AT545 automatic transmission
66 passenger

[EastCoastCB]

IDK why they used three batteries. I've never had a problem starting with even one.
If you ever need more find a Rural King they have G31's for $80. They even have em for $82 at my local Freightliner shop.

Enjoy the bus, and welcome to the site.

[tylermay209]

Originally Posted by EastCoastCB

IDK why they used three batteries. I've never had a problem starting with even one.
If you ever need more find a Rural King they have G31's for $80. They even have em for $82 at my local Freightliner shop.

Enjoy the bus, and welcome to the site.

I took a look in the compartment - only the battery that started the power really needed replaced, but all three were showing their age. Once the dealer told me they'd knock the totaly battery price off the bus's already low asking price, I decided it would probably be the best bet to go ahead and replace all three.

From what I understand, the third battery was an option that the school district decided to spec on the bus new. I'm not complainng - more power for me.

[EastCoastCB]

Originally Posted by tylermay209

I took a look in the compartment - only the battery that started the power really needed replaced, but all three were showing their age. Once the dealer told me they'd knock the totaly battery price off the bus's already low asking price, I decided it would probably be the best bet to go ahead and replace all three.

From what I understand, the third battery was an option that the school district decided to spec on the bus new. I'm not complainng - more power for me.

I always replace em all when doing batteries.

Cool they knocked off the cost!

[Iceni John]

I've replaced most of my gauges with full-sweep gauges instead of the original quarter-sweep gauges that I really don't like, and I've used Speedhut for my coolant temp, transmission temp and oil pressure. I like Speedhut because you can spec the gauges any way you want, so it's easy to match existing gauges; I think Speedhut makes their tachometers in 2-1/16" and 3-5/8" sizes. I would have bought a Speedhut tach to replace my dying Teleflex tach, but Speedhut's lowest RPM tach is 4000 RPM with 200 RPM increments; I instead bought a VDO 3000 RPM tach with 100 RPM increments, much easier to read for my engine whose max speed is only 2100 RPM. There are a lot of Indian and Chinese tachs on eBay for cheap, but who knows how durable or accurate they are?

John

[PNW_Steve]

Originally Posted by tylermay209

Some specifications on my bus:

1989 Carpenter S/1753 International
International IDI 7.3L Diesel
Allison AT545 automatic transmission
66 passenger

Take a look at the link below and the companion tach's:

https://www.autometer.com/diesel-tach-adapter.html

It uses a pickup on the alternator to determine engine RPM.

[banman]

Look around for the School bus salvage/junk yard threads here.

You should be able to find your oem tach used from one of those sources.

[Booyah45828]

I have a pretty similar bus to yours.

In stock form, they used a 2 wire magnetic pickup that screwed into the flywheel housing, which created a signal off the starter gear teeth passing by when the engine was running, and ran that signal up 2 wires into the dash board to the tachometer.

I looked high and low for a nos diesel tach for our gauge clusters, and never found one.
I did find a bunch of listings for nos tachometers for gas engines, though. So I eventually settled, bought one for a gas engine, and then used a dakota digital tach adaptor to act as an interface and get it to work correctly. My sensor is actually a crank position sensor from a car, that I machined threads on the OD. It was cheaper to do it this way then to buy the correct sensor from international. It's worked without any issues so far for several years now.

Or you could get a used gauge, sensor, and wiring out of a junkyard, swap it in to your cluster, and then install the sensor in the flywheel housing. Look for a tach from a truck or bus that has the same instrument panel as yours, and has a diesel engine, because those should all work. That's what a guy on youtube did. We were in touch for a little bit when I was searching to install a tach on mine.

I didn't want to deal with used parts, and the possibility of receiving junk in the mail, so I did what I did.

As others have said, there are a host of aftermarket options to choose from as well, but I wanted something that looked oe, so that's what I went with.