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kate lara
Novice
Aug 23, 2007, 12:44 PM
Post #1 of 6
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i have a 1973 dodge 360 sportsman class c motorhome that vibrates at high rpms, it doesnt have to be moving to do this. got any ideas as towhat could cause this
thanks
kate
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Aug 24, 2007, 5:08 AM
Post #2 of 6
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Re: engine vibration
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This could be a lot of things but start by looking at the engine and belts while running at idle. I'm most concerned with the lowest pulley that is the harmonic balancer and power source for all belts and dampens vibration made normally by an engine and they are mounted on the engine's crankshaft. If you notice any wobble there it must be checked out right away as if that fails the engine will self destruct. Not to scare you but DO rule that out,
T
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kate lara
Novice
Aug 28, 2007, 9:35 PM
Post #3 of 6
(2738 views)
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Re: engine vibration
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hi, well I got that bolt out, now one more question... It looks like there is some play in the timing chain, how do you tell if it should be replaced or not? 360 dodge 1973 motorhome
thank you so much for all your help so far.
kate
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Aug 29, 2007, 7:50 AM
Post #4 of 6
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Re: engine vibration
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How do you suspect the timing chain? Do you know when it was done?
Ways to tell how good it is now: It's tricky. If it's never been done in a 1973 it's due - period. They can behave well till they fail. Some engines will be destroyed with a total failure and that might be one of them. I think with that engine you can pull out the mechanical fuel pump and put your finger on it and feel how much slack it has when you turn the crank such that the slack is on that side - kind of like checking a bicycle chain if you will. Another is to remove distributor cap and turn crank by socket in damper one way then the other with the timing marks where you can see them. If you see 5 degrees or more of damper movement without rotor movement at distributor that is a good clue that it's off spec.
Original timing chains used nylon for gear ring on cam gear. This stuff doesn't last well or tolerate heat well. Replacements should always be all metal. Always replace both gears and chain not just a chain or one gear. If you go there it's a handy time to just replace hoses, waterpump (it's off anyway) and anything that's off anyway is good to update then. Change the oil at once with this job as it's easy to get shavings from cleaning up gasket surfaces into the oil pan. Parts for all this are not all that expensive and depending on how easy it is to get at things not the worst job if you have good tools.
Are you planning to do all this work yourself?
T
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kate lara
Novice
Aug 29, 2007, 9:35 AM
Post #5 of 6
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Re: engine vibration
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Hi again, I already have the timing cover off, I think I am going to replace the chain and gears, as you said. I sure dont want to go thru all this again. I will also replace the water pump and hoses. Any other tid bits of auto wisdom that might help me thru, would surely be appreciated.
Thanks
Kate
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Aug 29, 2007, 11:15 AM
Post #6 of 6
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Re: engine vibration
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Tips: Clean all gasket suraces real well. Stick new gasket on timing cover and water pump with Permatex gasket maker and let it dry so it's stuck pretty good. Use golf tees, screwdrivers - whatever to hold gasket lined up with the holes and keep holes free of any gasket cement. Use the cement to stick it on more than to make a gasket so use sparingly.
Take all bolts and with a wire brush wheel clean off the threads. Put a smear of silicone grease on threads except for ones to water jacket then use the sticky brown gasket sealer that is like thick molassis - I know it as Indian Head gsket cement. Comes with brush in cap. The silicone grease is great on metal gasket surfaces so the gasket will not stick permanantly to the engine side of things if you are ever back there again you'll be glad you did. Just a smear. It makes a great belt dressing also and keeps them quiet. They may slip for a short while and then they actually grab better. I put silicone grease (toothpaste type tube) in a spray paint cap and apply with a flux brush which is just a fairly stiff little paint brush and cheap.
Use just a smear again of silicone grease (it's rubber friendly) on inside of cooling system hoses and they won't get the Chrystler crust and hoses can come off easily years later if needed.
Chain all back on and lined up with arrows as directed - good time to be sure of this - then move on to the rubber gasket to be placed on the oil pan as directed a tad of gasket maker at the ends. There should be alignment pins like 14 inch or so things on the timing cover or the block that must line up. You have to push down against the seal at the oil pan which can be a PITA but it has to be right. If unsure go back now and fix that. They are a pest most of the time so keep your valuim handy (just kidding) and go on with all the other steps and parts in the order you took them off. Make sure all belts and hoses are lined up and brackets in the right positions so belt pulley alignment is exactly right.
You probably took the radiator out and all kinds of crap for that but when it's back in and cooling system tight pressure test with air at all gaskets and hoses for leaks. A small amount of foam may show up at gaskets when using soapy water as the test which is ok if limited as when coolant gets in they will swell and be fine. Start engine when you are sure things look good now before filling cooling system. If it runs you may proceed. If it doesn't then you will have an easier time going back to find out what went wrong.
Go ahead and fill it all up and finish off the job. New belts and hoses should be rechecked for tightness after it has run and warmed up as hose clamps feel snug when rubber is cold and may need a tad more when warm and then you can forget them. Belts should be tight but never too tight - just know that new ones will require readjustment and it's near impossible to overtighten on purpose to account for that. Things with bearings don't want the belts too tight.
Ahhh! I have to go this second and don't even have time to proof read what I just wrote so hit back with any confusion I've caused,
T
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