617 timing chain tensioner spring replacemt

[JDmills]

I am about to replace the tensioner spring as a matter of principal on my '84 300TDT. It has about 266K on it and by using the Cam alighnment marks the timing chain shows 2.5* BTDC..

Having never had the tensioner apart, and not really wanting to take more apart than necessary, can I pull the spring out and replace it, with out removing the Valve cover again? Or does the tensioner/ratchet/spring all need to come out and reassembled outside the block, and then reinstalled?

[300SDog]

Best regards to my old 240D. Meanwhile are you talkin about the rail or actual hydraulic tensioner on the 617 located under/behind thermostat housing? Am not aware tensioners were rebuildable. And at 2.5* stretch with 266k its safe to assume somebody's already replaced the tensioner when they did the chain. If throwing in new spring "rebuilds" the tensioner thats news to me. My understanding it hydraulic tensioner operates off oil pressure delivered through oil gallery flow direct from oil pump. And the spring does little more than prevent tensioner piston from sticking with valve partially closed. Otherwise ye never need to pull the valve cover to access the chain tensioner.

[JDmills]

Originally Posted by DieselDog

Best regards to my old 240D. .

It is still here at the ranch.. and i have yet to get it done... although it might happen some day soon, at least it has not gone to the scrapyard!!! there are still some rust issues to attend, like the whole passenger side seam that runs between the floorpan and lower door jam.. as well as some heater/wiper issues.. I think I got the rear end fixed, and figure I will run the engine as it is for a while... (I plan to set the idle up a bit and it doesnt make much noise)

[JDmills]

Originally Posted by DieselDog

. If throwing in new spring "rebuilds" the tensioner thats news to me. My understanding it hydraulic tensioner operates off oil pressure delivered through oil gallery flow direct from oil pump. And the spring does little more than prevent tensioner piston from sticking with valve partially closed. Otherwise ye never need to pull the valve cover to access the chain tensioner.

I guess I had understood that the spring will wear/weaken, which is actually a part of the cause for timing chain failure... And the timing chain tensioner rail was/is supposed to be a long wearing part... Now I am not so sure about my understanding.. time to go do some more reading ...

[300SDog]

Originally Posted by JDmills

I think I got the rear end fixed, and figure I will run the engine as it is for a while...

Yep, left rear axle was played i thought. Also listen for piston slap at speed when ye drive it. Busted odometer says 289k(?) probly closer to 320+. Am glad it found a decent home, was Annapolis Navy officer's car spent most it's life in Maryland. Whatever rust you're lookin at came from sittin 2 yrs outdoors in New England.

at least it has not gone to the scrapyard!!!

Damned junkies told me over the phone they'd gimme $150 for it *delivered*..... Happier given it away for FREE knowin it's appreciated and kept on the road.

That would be due in another two years, but if you have all that stuff off and the enthusiasm and time, do it now. Never put it off.