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77 dodge sportsman 225
https://slantsix.org/forum/viewtopic.php?t=35231		 Page 1 of 1
Author:  nfsus [ Wed May 06, 2009 5:55 pm ]
Post subject:  77 dodge sportsman 225
ok, where to start?. i have a 77 b-200 sportsman van with a manual transmission (3 on tree), 225 ci, carter carb and so on. what has happened is that this van has started to have what i thought was compression issues, but i did a test on it today and to my surprise i got 120psi on all cylinders within 10 pounds or so. i did this test using the starter, all plugs pulled out and the engine was cold.

the issue that i have been having is that it has started rolling backwards in the stop jerk motion of a worn motor. i am not sure if this is motor or clutch??? i am at a loss at this point. the old thing has never been reubilt, purs like a kitten and runs damn good, but with it slipping i am not sure that it is in need of a rebuild or not. i do have another motor sitting in yet another van if needed.

anyway, i think that this site is awesome! and thanks yall!!
Author:  SlantSixDan [ Wed May 06, 2009 6:49 pm ]
Post subject: 
Welcome on the board. "Rolling backward" when, exactly? How do you get it to roll backward? And please describe this "stop jerk motion" in greater detail.
Author:  nfsus [ Wed May 06, 2009 7:03 pm ]
Post subject:  rolling , but not to buffalo
what i meant to describe is what happens when you are on an inclune or slight grade and have it in gear and not running. in 1st gear or reverse, when parked on this incline it will slowly jerk start stop and roll back down the inclune while the motor is turning. at this point the motor is supposed to be off, holding the van in place.
Author:  Reed [ Wed May 06, 2009 7:17 pm ]
Post subject: 
So what you are saying is that, when parked on an incline, you used to be able to shut the motor off, leave the transmission in gear, not set the parking brake, and the compression of the motor would keep the van from rolling? But now it doesn't?

It sounds like the jerking motion you describe is the motor turning backwards through the four stroke cycle and the vehicle slows down (jerks) on each compression stroke. I don't think any vehicle is supposed to work that way. As far as I know you are always supposed to set the parking brake to keep a manual transmission vehicle from rolling on a hill.
Author:  nfsus [ Wed May 06, 2009 7:45 pm ]
Post subject:  thanks
that is exactly what i am talking about! thanks for the info. also does it matter if you do the compression test cold??? ambient air temp was 75F. does it matter? 120psi seems like alot, but i am not a mechanic.
Author:  Reed [ Wed May 06, 2009 8:22 pm ]
Post subject: 
120 PSI is actually a little on the low side for compression, but fine for a daily driver, especially if the motor is cold.

Stop tyring to park your van with the motor, use the parking brake. That is why it is there and why it is called the PARKING brake.

I recommend you give your van a full tune-up and reset the valve lash.
Author:  MichaelS [ Thu May 07, 2009 6:31 am ]
Post subject: 
I have been doing the put it in gear and leave it style of parking since i learned to drive. When i got myself a Ford ranger 3.0 V6 with manual tranny I did the same thing. When it was still fairly new it did the slow roll on a slight incline one and I could watch the fan blade slowly turn. I think it has to do with were the pistons are and if it has a chance of moving before much compression builds up, then its momentum that will keep it moving, if the hill is steep enough. I put another hundred thousand on my Ford with no problems so I don't think its a sign of bad things. I do use the parking brake if on a hill now .
Author:  MilwaukeeTech [ Thu May 07, 2009 4:14 pm ]
Post subject: 
For what it's worth, I believe that a compression test won't be particularly revealing in relevance to the issue "nfsus" describes. Seems more like a situation for a leakdown test.

Also, FWIW, I agree that Mopar put a parking brake in there for a reason.
Author:  Reed [ Thu May 07, 2009 6:56 pm ]
Post subject: 
Quote:
I have been doing the put it in gear and leave it style of parking since i learned to drive. When i got myself a Ford ranger 3.0 V6 with manual tranny I did the same thing. When it was still fairly new it did the slow roll on a slight incline one and I could watch the fan blade slowly turn. I think it has to do with were the pistons are and if it has a chance of moving before much compression builds up, then its momentum that will keep it moving, if the hill is steep enough. I put another hundred thousand on my Ford with no problems so I don't think its a sign of bad things. I do use the parking brake if on a hill now .
Leaving a manual transmission car in gear when you park is a great bit of added insurance to keep the car from rollingthe car won't roll, but you are supposed to use the parking brake to keep it from moving.
Author:  Rug_Trucker [ Thu May 07, 2009 7:24 pm ]
Post subject: 
chain it to a fire plug! :lol:
Author:  Reed [ Thu May 07, 2009 10:19 pm ]
Post subject: 
Quote:
chain it to a fire plug! :lol:
But you better do it quick before it rolls away! :roll:
Author:  hantayo13 [ Fri May 08, 2009 5:57 am ]
Post subject: 
my 81 d-150 has no cables for park brake if i park on hill i use a block/chock to keep it there ...the wife's 05 scion with 5 speed manual ...we always use parking brake on hill...if not it will jerk/stop down even slight grade...

keep on roddin'
Author:  nfsus [ Fri May 08, 2009 2:15 pm ]
Post subject: 
ok! it seems like a unamious decision, parking brake it is. course now i have to fix that too....ahhh mopar fun
Author:  Reed [ Fri May 08, 2009 9:33 pm ]
Post subject: 
You know, you should always keep the parking brake in working order. On automatic cars they are called the E-brake, or EMERGENCY brake. If the hydraulic system ever completely fails, then you at least have the emergency backup of the rear drum brakes. Brakes are the one system on your car that you should never skimp on and should always keep in tip top order.
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