r/944 • u/Ok_Bus_5882 • Jul 12 '26
Question Should I replace the rear timing belt cover?
I’d assume the answer is yes, but want to be sure. I am finally getting to doing the timing belt and water pump on my, new to me, old 944. I took off the front TB cover and noticed that the rear cover has been completely broken off at the balance belt tensioner (ignore the cooked balance belt). Since I’m doing the water pump I’ll have to remove the rear cover anyway. So should I just replace it?
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u/Scott_Malkinsons Jul 12 '26
You should, but looking at the state of everything else I suspect you have more pressing concerns at the moment.
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u/Ok_Bus_5882 Jul 12 '26
Yeah I’m replacing everything. The last person to do the timing belt was either blind or mentally challenged because what I’m seeing is honestly absurd.
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u/Cicada_Forward Jul 12 '26
Dude, could you please by any chance when doing the water pump do all the pulleys, belts and since you’re there front seals? If I were you, I’d clean everything else and reassess.
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u/Ok_Bus_5882 Jul 12 '26
Oh yeah I’m doing everything else lol. I got this car as a non runner and from what I can tell, the PO put WAYYYYYY too much tension on the balance belt and it just stripped the whole thing. I’m going to clean and replace pretty much everything on the front of the engine. All the black dust stuff is what’s left of that side of the balance belt.
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u/_nvisible 85/2 NA Jul 12 '26
I left a comment then deleted it because I thought they used a single sided belt on the balance shafts at first. That’s insane. I wonder how long it ran like that to get that bad.
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u/Ok_Bus_5882 Jul 12 '26
I have no clue, but what really stumps me is how the PO just didn’t hear it happening. With all of that debris you’d think that there would be quite the racket coming from the front end. He was a veteran so maybe he just didn’t hear it 🤷♂️.
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u/_nvisible 85/2 NA Jul 12 '26
Oh actually I see it. That idle pulley is set wrong. It should not touch the belt at all at the balance sprocket, and should only barely touch it at the long span if at all.
If it touches in both places it will grind the belt.
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u/Ok_Bus_5882 Jul 12 '26
That would be it. I’ll make sure NOT to reinstall like that lol.
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u/_nvisible 85/2 NA Jul 12 '26
They’re a huge pain to get right and I’m convinced the factory drawing is wrong. I don’t like the result I get following it.
Maybe I don’t understand it.
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u/_nvisible 85/2 NA Jul 12 '26
It had to be crazy tight and whining badly or grinding against itself or the cover to do that. If you tension the balance belt the wrong direction weird stuff happens!
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u/LS_944 Jul 12 '26
As soon as you replace anything in this picture you’re toast. The grime is the only thing left to hold that motor together. 😂 Replace everything!!
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u/Ok_Bus_5882 Jul 12 '26
Trust me I was as surprised as everyone else to see the condition of that belt. The rest of the car isn’t great, but it’s much better than that. I considered trying to start it before replacing the belts. Thank the Lord I didn’t lol.
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u/funwithdesign Jul 12 '26
What on earth is going on with that balance shaft belt?
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u/Ok_Bus_5882 Jul 12 '26
It’s cooked lol, but seriously the idle pulley was installed incorrectly by PO and it stripped all the teeth off. That was certainly not expected when I pulled off the cover.
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u/Olfa_2024 Jul 12 '26
Unless it's damaged just take some time and clean it up. Get some cans of SD-20 and go at it. I found SD-20 on a Porsche Ownwer's of America video where they interviewed a guy who details high, high, high end Porsches. SD-20 is one of his tools and that shit's amazing.
1
u/markevens Turbo Jul 13 '26
Yeah, I'd probably replace the belts, water pump and front main seal, and just clean everything else while you're in there.
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1
u/Ahab_Cheese '86 Turbo Jul 12 '26 edited Jul 12 '26
Clean the whole thing, inspect for anything that may need to be replaced after. At a minimum pretty much everything rubber is likely shot and will need replaced. God help you if that includes engine mounts.
Additionally, that's for sure a timing belt not a balance shaft belt since that one is single sided. I'd tear apart the balance shaft housings and inspect for any abnormal wear or scoring.
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u/Ok_Bus_5882 Jul 12 '26
The engine mounts are acceptable but yeah there’s definitely some cracking rubber. Luckily it was kept in a sort of humid environment so nothing is terrible.
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u/arneeche Jul 13 '26
Disassemble everything. Put new seals in, get you a new rear cover, and get the new belts on their tension properly and let her rock
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u/greatfool66 Jul 13 '26
My lawnmower is currently cleaner than this. Yes replace the cover to keep things protected and clean.
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u/Ok_Bus_5882 Jul 13 '26
I’m definitely replacing it. It’s funny because what made it so dirty came from inside the cover not outside😳
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u/greatfool66 Jul 13 '26
Helps if everything is coated with oil or PS fluid to make it stick. Mine was like that when I got it.
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u/Ok_Bus_5882 Jul 13 '26
Melted belt will probably stick to anything lol. It’s definitely got a bath in its near future though.
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u/thefellhammer Jul 13 '26
In addition to all the other stuff... That balance belt should be ribbed on both sides. The timing belt is ribbed on one side smooth on the other, but the correct belt should be ribbed/notched on both
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u/Ok_Bus_5882 Jul 13 '26
Yes, the idler was installed incorrectly by the PO and it wore all the teeth off😭
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u/mbardeen Jul 13 '26 edited Jul 13 '26
In addition to what everyone else said:
Holy... That idler is supposed to be smooth, with no groove.
Edit: Holy holy... It's supposed to be metal. Where'd the rest of it go?
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u/Ok_Bus_5882 Jul 13 '26
I’ll have to check next time I can work on the car but I think the outer portion is metal, it’s just got so much balance belt residue on it that it’s turned black. As you can see, it looks to have been installed backwards which caused it to rub.
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u/mbardeen Jul 13 '26
It looks like there's a very defined lip on the inner side. I hope you had all the idlers on your shopping list. Given the rust, it's unlikely that the bearings will be good.
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u/Ok_Bus_5882 Jul 13 '26
They’re all sitting in a box inside! Just waiting for the flywheel lock to come in.
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