450C don't move

[timmtnman]

Looking to buy a 1981 450C. It runs good but doesn't move. He says it builds pressure but blows the cooler hose off when the clutch is released. Any ideas what would cause this to happen or is something major wrong inside it. Would like to know what I'm up against if I buy it. Thanks

[LeonardL]

Well that's a new one for me. I would suspect it has an issue inside the HLR causing back pressure to blow the cooler line off. If you're looking to buy it then I would set my price accordingly. You may need to go in deep to fix it.

[dtoots1]

Believe that i would check and see if BRAKES are locked or frozen?..considering that no mention of issues UNTIL clutch is released? to check that you mite try to pull it backwards a couple feet or raise it off ground? see if tracks move

[Jim B]

I agree with Leonard at this point. When the clutch pedal is pushed about halfway down, the clutch valve dumps the HLR oil, stopping travel but leaving the power shaft with live power from the engine clutch. It could be issues in the HLR valves or a bypass valve causing the problem. Need to be sure the right hose is being used for replacement for one thing. It may look like heater hose, but it isn't, it has to be rated for oil service and pressure. Perhaps someone who has experienced the same problem will be along.
Jim

[timmtnman]

Thanks for the insight on this. It does roll so brakes aren't the problem. What's an estimated cost on the reverser if you go deep into it.

[cordlesscarpenter]

If the trans cooler hose is blowing every time the clutch is released, I would first chase down the problem by starting with the low hanging fruit. My first inclination is to look for a blockage (think clogged filter). If changing the filter doesn't work, it could be something as simple as a valve (think needle valve or more likely, a bypass valve) not operating the way it's suppose to.

Cost of repairs can vary quite a bit. If it turns out to be something inside the trans, it would likely be in the front half which would be accessible by removing the top cover but you may not be able to replace the failed part without removing other large components. If you did the work yourself it could end up being as little as $20 in parts, a bunch of time and a few curse words along the way but to have a shop troubleshoot and repair/replace that same $20 part, it could end up costing you hundreds but more likely thousands of dollars. I'm not trying to scare you, just laying out the facts from my experience, which drives home the importance (in my subjective opinion) of going after the low hanging fruit first.

The oil leaves the trans and goes to the trans oil cooler which has a few spring loaded bypass valves, then through the filter and returns to the trans.

If you're going to take a crack at it, find out which cooler hose he is telling you is being blown, if it is between the trans outlet and cooler inlet then I'd start by replacing the filter (the one that sits in front of your radiator just behind the front grill). If that doen't work, the next thing I would do is run through the differential pressure checks on the inlet & outlet lines of the cooler (see the service manual) to see if the bypass valves are operating correctly. If it is the line from your filter back to the trans I would say it's likely something inside your trans that is causing the back pressure (think "clutch control unit" which controls the flow of oil and is inside your trans).

I've cracked open a few trans cases but never done any extensive repairs so I'm no help in that department and certainly no expert. I'm sure there are people on here who have rebuilt these or at least made repairs without pulling anything major but I'm not one of them (yet ). The service manual has a lot of detailed information to help you attempt it yourself though. Like anything else, the more you study it, the simpler it will become, the more you'll understand it and the more confidence you'll have in troubleshooting & repairing it.

If you end up working on the trans and at some point drain/change the oil, I would recommend pulling the strainer/filter at the bottom (passenger side), cleaning it and putting fresh HYGARD in. If you do pull this strainer, take a really good look in there (you can see part of the bottom of the trans case), make sure there aren't any "treats" for you in there floating around.

[timmtnman]

Thanks for the detailed information.