Hi guys,just an idea I might try and after thoughts or inputs....I just fitted a TR engine to my TP,nice and quiet,even at start up with the ratchet tensioner! Now I have the original TP engine which is a decent old engine,except for the flogged chains,guides and oil pump bore where the tensioner fits into which is worn. i have some good used chains,guides,oil pump body etc I have laying around,so I thought I may as well put the best of everything into the old TP engine for a spare and throw out all the junk.
So after all that ramble this is what I'm thinking....after the timing chain is fitted with all the guides etc,there is about 3 to 5 mm clearance between the body of the oil pump and the hydraulic tensioner. Obviously this is free to flog around and play the classic Magna music we all know on start up until oil pressure takes up the slack,so has anyone tried shimming up this clearance so that even without oil pressure the chain is kept lightly tensioned? Sure,as things wear it will still rattle on start,but at least your starting at a good point and the oil pressure should take less time to do its job.....what ya reckon?

the oil pump has a pressure relief valve set to specs

if you shim
the only places are at the base of the spring in the pump
or in the shaft of the tensioner ..is that right

i think you would need an enginering degree and much knowlage of hydraulics

to work out

pressure of spring needed so as not to interfere with the pressure valve specs
the diameter of the shim so it doesnt get stuck in the pump shaft under cold and heat
if you have to change it

only thing I would possibly do is replace the old spring
with a new one or at least a better one and see if that helps
if you try to strech the spring it wont work ... i tried


mitsubishis answer to this problem was the rachet system ..what a pain

No,I wasn't going to shim the springs,just make a spacer to slide over the OD of the tensioner shaft ( its the section of the tensioner thats roughly 10 or12 mm diameter) prior to fitting it into the oil pump so once everything is assembled the spacer pushes the tensioner out far enough to keep a light pressure on the timing chain,so the chain will be unable to slap around at start up.

you ask intresting questions

just woke up to this problem at 5 am
there must be a reason why mitsubishi didnt try so simple a solution as you have suggested
but I dont know what it is

as a guess for the TP motor Mits people must have worked out the spring has eneough coils to take the shock of the first touch of the tensioner to the chain as it whips to give it recoil so as not to shock the parts to break point
but give the right time for the pump pressure to then push the tensioner on to the chain and do its job as it continues to rotate

so heres the challenge
can you get the motor rebuilt to a stage for bench testing
to rotate the motor to the right revs without starting
full sump of oil and timing cover off
then calculate the shim thickness that works

I guess the only reason Mitsubishi didn't fix it using this idea is because they came up with the ratchet tensioner,it maintains a light tension on the chain at all times,and as long as the ratchet does its job it provides a positive stop and the chain can't flop around and make a racket,even at zero oil pressure,and it takes up slack as wear and tear occurs during years of use. My idea would only give you a nice starting point,as things wear there would still be some slack,but I would think it would be a lot less than without the spacer idea. I have the engine on a stand,it's built up but no sump or timing cover on it yet,but I don't have anything capable of turning the motor over to simulate it running at idle like you mentioned,but if I turn the motor over by hand you can see what's going on at start with no oil pressure....as you rotate the crank it of course pulls the timing chain under tension on the drive side and rotates the cam,but,there is a point on the cam where there must be a few lobes on the valve closing side and the cam wants to rotate under its own steam,then all of the sudden the side of the chain that was under tension becomes slack,the tensioner gets pushed into the oil pump body until you continue to rotate the crank and the the chain snaps back to being under tension on the drive side again and the tensioner extends out of the pump again,that poor little spring in the tensioner really only seems capable of pushing the tensioner out when the chain is driving the cam,but it doesn't stand a chance of pushing it out when the cams pulls that side of the chain tight. This seems to be the cause of the racket these things make at start and at idle as we all know. I don't think that by making a positive stopper like my spacer idea would cause any probs,at the end of the day it's the same basic principle as the ratchet setup,except its not automatically adjustable. I think there would be a few better fixes for the prob,but at the end of the day I guess the first gens are in the low buck fix end of things, I will spin up a small alloy bush to space up the tensioner,but really anybody could try this idea when doing a timing chain replacement using a bunch of flat washers to suit their engine...now that's as low buck as it gets! Unfortunately this is only a spare engine and won't get used for quite a while,but I'd love to see somebody give it a go at the next chain replacement to see how it works.

Just a lot easier to get a oil pump off a late TP or even later Tr/Ts and swap it out and all is well and no risk of a engine failure if the experiment was to fail at some point. You then get balance shaft chain ratchet to boot as well.
You want to do a helluva lot of testing before you put the engine into regular service. You would have to think with the amount of years Mitsi/Chrysler used this setup that before the ratchet idea hit home they did not have engineers thinking of other ways to fix it.Vee

Adding extra washers to the shaft of the tensioner is an old trick I've done a few times on the old 2L Sigma engine with good results. Stops the chain flopping about and hammering the tensioner against the oil pump body while the engine starts and before the pressure builds up.

Well there you go! Nothing new here,I thought I was on to something.....I really don't see how it could do any harm,after all,the effect is basically the same as the ratchet setup,both provide a positive stop to keep the chain under tension at start or with idle oil pressure. I had a good early oil pump body, that's why I did this trick,I didn't want to fork out for another oil pump etc etc,I'm just using the best of what I have to put in my old spare engine. I actually finished it today,spun up a .300" thick spacer,10 mins work,no chain flop when you rotate engine,I would love to give it a run one day,but in no hurry,the new engine is going really well. Cheers

Just a lot easier to get a oil pump off a late TP or even later Tr/Ts and swap it out and all is well and no risk of a engine failure if the experiment was to fail at some point. You then get balance shaft chain ratchet to boot as well.
You want to do a helluva lot of testing before you put the engine into regular service. You would have to think with the amount of years Mitsi/Chrysler used this setup that before the ratchet idea hit home they did not have engineers thinking of other ways to fix it.Vee
I don't think the balance chains have a ratchet setup,its similar to the early timing chain tensioner with a spring and oil press.....at least that's what the TR engine had in it,maybe other models were different. Like I said, I wasn't going to waste time searching for a decent late oil pump and buy the appropriate timing set,Im just using what I have,it's all used stuff but its still good enough to use,especially the oil pump,it was like new.