Hi Guys,


Found a 1975 KW with a big ole 3408 under the hood. What is the history on these engines? Thanks, John

They were more or less a V-8 version of the popular 3406 engine and was used in several Cat machines along with it used as a truck engine.I have worked on & rebuilt lots of them years ago but just can,t recall a weak point in them.It never went over as an over the road truck engine for some reason as the 3406 was the favorite.They were a powerful engine in a truck and we had a local customer with one in his conv. KW and was a beautiful truck that all admired.They used plenty of fuel compared to todays engines but if you plan on buying this truck check it over close as is normal and if used just for local hauling it would make a powerful decent truck to buy.

John I have also seen a few old Peterbilts with the 3408 engines in them. The guy that owned them that said when they were left alone with all of the stock rack travel setings and A/F control settings they just did not have enough power to offset the additional weight of the engine. That is why the 3406 engine was so popular, better power to weight ratio and a lighter weight engine meant more frieght you could haul. He had his cranked up to the point that they bellowed black smoke at an idle. He pulls drop deck trailers accross I-80 and he likes the power when pulling the "3 sisters" in western Wyoming. Can you guess what the weak spot is in his trucks...................trannies!

That would be it SJ, local and shows. It has 4 axles with the tag, exhood, 60 inch walkin bunk, just massive. Kansas Cat says it's too much truck for my D4. He wants it to haul his trackhoe. Will get some pics next time I go see it. Thanks, John

We where writing at same time Chad. Yep the Grandson of the owner said if you pop the clutch it likes to break the drive line. It was used for hauling D8's and 9's along with scrapers. Thanks, John

They actually were popular in trucks if you could afford them, pretty pricey to start with, but with a little tweaking they would roll, past everything except a fuel stop, fella around here ran one jacked to 750 horses, so he claims, got 2 miles per gallon, nothing got around him.

I remember talking to a Cat service rep back in 1977, he told me that one of his previous jobs was testing the pre-production 3408 fitted in a Kenworth on a regular run hauling Coca-Cola to Anchorage! So a truck was the test-bed for the 3408 which was to become a very succesfull Plant and Marine engine. We are currently overhauling one in a fishing boat which has done 50,000 hours and only had one top-end overhaul.
It is true though, that where payload is important, the 3406 is big enough.

Got pics of engine and truck, posting in the 4 sale thread. John