I am planning to re power my 621 23h from the d336 to a 3406b. I have herd of guys doing it before but don't know any one personally who has. Do any of you guys have experience with this. Is there a simple way of mating the back of the engine. Can I buy parts or do I have to make everything from scratch? Thanks for your advice.
I can't contribute anything regarding how things will mate up, but I ran a 621 that had a 3306 installed.
There was a factory retrofit using the 3306. That D336 was a pile.
Retro fit I've talked to the dealer at length about the factory retro fit and they can't tell me anything. If I had a part number it may go somewhere. Or even if someone had a drawing. I guess it may just turn into trial and error.
I can't see anything regarding re-engining a 621 of 23H prefix, but this might interest you. I found it under 621 2DB prefix. REHS3566 details the modifications necessary to repower various scraper models from 621 thru 627 with a 3406 engine - however the list does not include 23H. Ask your dealer to help you with a copy of that document. It may not be 100% what you're looking for but it's more than you have right now.
I'll keep looking for the factory swap information. The following is from the ATHS website in 2011: CATERPILLAR 1676 - D336 4.5" bore, 5.5" stroke 60deg V8 D336 was used in 621, 621J motor tractor scrapers and the 980 wheel loader. The 621 was 300hp and air to air aftercooling The 980 wheel loader was 225hp and had no aftercooling, ( I think it was 225hp ?) The engine gave reasonable service in the 980's, the 980B was powered by a 3306 engine. But the 621 / 621J was released with the D336 engine and at the time a new design 8 speed transmission which had 2 converter gears and 6 direct drive gears and would believe some engine failures were a result of transmission operation (operator error). If they, the operator changed down incorrectly the engine would overspeed and usually at about 2700rpm the gear driven air compressor ( air brakes) would self destruct. With poor service life and difficult repair options as a result of the overhead camshaft drives CATERPILLAR released a engine replacement option using a 3306 6 cylinder engine at 270hp which result in a performance loss of 1 gear. We had several 1676 engines down here, 1 in a KW, 1 in a ATKINSON, 1 in a OSKOSH and another fitted to a ATLAS COPCO oil free air compressor. The KW disappeared ? the OSKOSH was a service truck on a dam job and we did not see it. The ATKINSON was a twin steer bogie drive prime mover built especially for heavy haulage by L ARTHUR a trucking company that worked for CATERPILLAR moving all the machines of the whalf to the dealer. We rebuilt it once after the bigend bearings failed, on disassembly it suffered the same problems as other D336 had which was the connecting rods thrusting into the webbs of the crankshaft. Several years later CATERPILLAR released the D346 5.4" bore 6.5" stroke 60 deg V8 for larger scrapers and dump trucks and athough much bigger and heavier engine looks very very similar in appearance and component layout.
We have a winner I think... From a post back in 2012 on this very forum, StanRAUUS said it was Special Instruction - Installation of 8N6332 Engine Arrangement From SMHS7551 621 - 23H, 15U / 623 - 52U HeavyEquipmentForums
So that crank/rod wear was "common"? Back when we had a few of those dealer seemed to act like they never heard of the problem. Think they tried to say it was from worn thrust washers on the mains. Thing is the crank end play was never out of spec!
I was quoting another poster from the ATHS forum in that thread. All of the ones that I have had personal experience with have had crank problems. You know it's pretty bad when Cat gives up on one of their own and makes a retrofit to do away with it altogether.
There was a local guy who was working on the idea of doing a repower of a 980 years ago. His engine of choice was a 8V-71 Detroit! He hated anything with Cat Yellow paint on it and was dying to put an Alpine Green engine in one. Not sure if he ever managed to complete the repower. I'm sure it would have been a good "up-grade" if moving from 225 horse to 318 horse of a "stock" 8V-71. Heck a 6V-71 would have been a good option at 238 Horse and physically a little more compact than the D336!
Well, it's proof that age mellows a fella. I used to hate those Detroits with a passion when I had to use them. Now, it's not bad to jump in one of two that I have left and hold it on the floor.
Problem would be torque, I didn't do any research but I kinda think the CAT engine would have a torque peak at a lower RPM than the Detroit... Race cars develop oodles of horsepower at like 9,000 rpm, LOL
One place I worked bought an old KW with an 8V-71, had 5+4 transmissions... some of the whiners couldn't drive it so the boss made me swap in a 13 speed Roadranger... fooled 'em and left the Brownie in her... 52 forward gears, didn't help much but it gave you something to do while you pulled a hill at 25 mph. The deep under was nice on rough jobsites though.
Engine swap Thanks for the info d9gdon. I had my dealer rep look it up and he can find nothing. I'm new to this forum. Is there a way to get in touch with stanRAUUS? I looked up his post and he had a drawing he said. Thanks.
I found a Service Magazine SEBD1934 dated 01/10/1979 referring to the engine change. The text reads as follows...... 621 Tractors ( 23H, 15U ) and 623 Tractors ( 52U) Description of Change: A 3306 Engine Arrangement has been released as a replacement for the original engine used in 621 Tractors (23H and 15U) and 623 Tractors (52U). The 4.5" Bore 8 cylinder engine originally used in these tractors is no longer available. When installed, the new engine will use the existing radiator and air-to-air after-cooler on the machine. Adaptable To: The new 8N6332 Engine Arrangement (Replacement) is adaptable to all 621 Tractors 23H1-up and 15U1-up, and 623 Tractors 52U1-up. A Special Instruction, Form SMHS7551 is available with complete information for installation of the new engine. . I suspect that the Special Instruction SMHS7551 was only ever available in paper form and never found its way into the online resources. It happens occasionally. See if your dealer can get a copy from Cat's literature library or send Stan a Private Message (PM). If you click on his name in the thread that was linked above a dropdown box will appear with "Private Message" as one of the options, another option available in that same dropdown box would be to email him.
We have several of them we converted in our own shop using 3306's, that we would like to move along with some 621B's just don't have the work for them or operators any more. plus a few 621a transmissions.
Yair . . . I saw an 8V-71 POWERED 621 egg-beater (Johnson elevator) working on a road job out near Cunnamulla probably around 1972. Apparently it was a very successful conversion after a series of catastrophic failures in what then was a fairly new machine. Cheers.
Hi Duramax Have you sold all cat 621 with 3306 in ? thanks Alan
No we still have some available.
Sorry thought I replied along time ago yes we still have them.
Finally found someone else, my grandpa had 3 621s he repowered with 8v92’s talk About a HUGE power upgrade, I ran them for quite a few years before we finally upgraded, my dad said the 336’s were the biggest pile of junk engines cat ever made