1981 International school bus

[pwalker]

How good is a 345 gas engine and what type of transmission should go along with this type of engine?
Any insights would be great
Thanks

[cowlitzcoach]

The IHC SV345 was one of the best medium duty truck gas engines ever built.

It was over built for strength, reliability, and ease of repair.

An SV engine weighs as much more than a GM big block as a big block is over a GM small block.

The engine has steel timing gears, full water jacket for very efficient cooling, hardened valve seats long before unleaded gas make it important, and over built bearing seats for the crank and main bearings.

Their one shortcoming was the oiling system for the top end had some drawbacks that were not a problem if the engine say daily use. When they sit around for a long time if the oil system is not pre-lubed before the engine is turned you run the distinct risk of spinning out the cam bearings.

I have seen them go 500,000 miles with nothing more than very basic care.

I have seen a lot of different transmissions behind them:

• Allison AT540 and MT640 automatic
• 5-speed with 5th direct
• 5-speed with 5th OD
• 4-speed with 4th direct

I have also seen 2-speed rear ends with all of the stick shifts except for the OD transmission.

Fuel mileage with a stick shift was in the 5-8 MPG range.

Fuel mileage with an automatic was in the 4-6 MPG range.

The highest speed rear gearing I have ever seen with one was 62 MPH, the lowest speed gearing I have ever seen with one was 47 MPH. The most common top speed gearing was 57 MPH. With the 57 MPH gearing it could cruise easily at 55 MPH along I-5 in WA state and never have to shift down for any hill, even with a full load of passengers and gear. The 62 MPH top speed bus would need to down shift on the bigger hills and the 47 MPH top speed bus would never need to down shift until you got near the top of a mountain pass.

As far as the best transimssion is concerned, it is all sort of a matter of what is best for you.

When I was 27 the stick shift would have been my choice.

Now that I am 57 the automatic has a lot of appeal.

[EastCoastCB]

I don't like gas engines, but the 345 is a dandy.
I had one in my 73 Scout Terra and it was a REALLY reliable, strong engine. I think its still going. I wish there were something like the old Scouts and Scout 2's being built today.

[cowlitzcoach]

I don't know if I made my point adquately or not.

The SV345 was one of the best gasoline engines ever put into a bus.

It was relatively fuel efficient and extremely reliable.

What it wasn't was a speed demon.

50-55 MPH is the best speed for performance and fuel efficiency. Any faster and you use a lot more gas and every little hill requires a down shift.

So if you are looking for a bus that will not see many miles on the Interstate Highway System a bus with an SV345 would be a good choice.

If you plan on logging lots of miles at highway speeds a bus with an SV345 would be a very poor choice.

[EastCoastCB]

I can tell you've had experience with the ole 345 Cowlitz

[pwalker]

Thank you for your answers and your insight. I'm new to this and want to make a good choice. This sounds like a good choice for me as I plan to not do a lot of highway driving as we are doing a cross country trip and taking our time doing it. I should of mentioned that this bus I'm looking at has a 345 rebuilt engine with only 20,000 miles on it. So sounds like it would last for a long while. Is there anyway I could tell that this engine has been rebuilt as I only have the word of the seller, he seems straight forward, I just want to be sure is all.
I have to ask how would you pre lube the oil system as this bus would have to sit for a while during the conversion process. Would it just be easier to run it say once a week for a hour or so.

Thank you again for your input

[cowlitzcoach]

The easiest way to pre-lube an SV engine is to pull the distributor out.

Make a tool out of a long wide blade standard screw driver that can be put into a drill motor. You want something that is about the same size as the oil pump gear tang on the bottom of the distributor shaft.

Insert the tool into the top of the oil pump drive gear and then spin it up until oil starts coming out of the rocker arm assemblies.

Since it is a gas engine starting it up occasionally won't hurt it a bit. Once a month should be sufficient.

As to how to know if it was rebuilt the only way to know for sure is to see receipts to show the work was done.

As to how well it was rebuilt only time will tell.

If it was built by someone who knows IHC SV engines you should have hundreds of thousands of miles ahead of you.

If it was built by someone who doesn't know the unique challenges of an IHC SV engine it won't last very long.

The biggest issue is getting the oil holes to line up in the cam bearings. They have to go in just so or you won't get sufficient lube oil to the cam bearings. Even still, sometimes a file needs to be taken to the bearing to open up the oil hole a little bit to get the opening to match the oil passage.

The front seals have a tendency to leak. If a sleeve wasn't put on the nose of the crank or an oversized seal installed you will have a leak. If it does you can replace the seal and/or add a sleeve after the engine has been installed. It requires taking the radiator out and the bottom pulley but with a tilt hood that isn't that big of a job.

[pwalker]

hi cowlitzcoach
I want to thank you for the info! I feel better about this bus and will have a better idea as to what to look for now. I will keep you posted as to my progress with this adventure.
Thank You again

[c_hasbeen]

If I was going to chose a gasoline engine, this is the one I would choose, I have put a lot of miles, very hard miles on trucks with the 345.

I bought a truck that they said the engine was blown, I set the points put in new lifters and one rocker arm and used it pushing snow.

One thing I will say is it is getting more difficult to get rocker arms and drag links for steering and stuff like that, but not impossible and these parts are not stuff that will give you trouble but every 100,000 miles or more.

I have never had the IH 392, but I do know of a couple of rear engine gas buses with that engine. I do love that engine.

good luck.
Thanks
Cliff