|
Post by Armageddous on Nov 15, 2010 21:30:08 GMT -5
I'm somewhat stumped on this one. My motor is 90% complete being rebuilt when I called Subaru to get a new chain guide and they asked me: "Is it a WHITE 6.5mm or a BLUE 7.5mm?" I felt like hanging up and pretending it never happened. My chain guide is black and mutilated. I couldn't imagine measuring anything, even if I knew where to measure. For those of you who have rebuilt these engines before, and hopefully been through this.. help!?
Terry
|
|
|
Post by justyjuggler on Nov 17, 2010 14:09:31 GMT -5
Chose white because the old one wasn't blue...
|
|
|
Post by Armageddous on Nov 17, 2010 16:25:36 GMT -5
There has been a revelation. The Subaru parts guy stayed up all night (or so he says) thumbing through old parts catalogs trying to dig up information on the two different guides. Apparently the white 6.5mm is made for stock replacement of the chain and guide. The oversized blue one, 7.5mm, is made for use with over sized crank shaft main bearings. I guess the offset of the crank is enough to slack the chain and cause issues with the tension. Who woulda' thought!
Terry
|
|
|
Post by justyjuggler on Nov 17, 2010 18:24:54 GMT -5
I guess the offset of the crank is enough to slack the chain and cause issues with the tension. But, the crank doesn't change its position; it's always centered in the main bearings. Maybe your parts guy is gonna be up a while to figure this one out... Let us know what the diff is, what's this 6.5 vs 7.5 diff?
|
|
|
Post by Armageddous on Nov 17, 2010 22:48:36 GMT -5
Hm. I guess you're right, the bearings and the grind don't change the crank in relation to everything else. Well, I ordered a 7.5mm anyways. I would stipulate it's the padding thickness.
Terry
|
|
|
Post by Armageddous on Nov 18, 2010 21:55:59 GMT -5
Oooh it arrived! Here are some comparison photos of new, old, and the one from my carb motor. Anyone ever consider that some oil pressure may be lost at this chain guide where it meets the block? There is no gasket and it relies on the flatness of the metal to seal. The only problem being that the guide is aluminum and the block is cast. Further more, both of my old guides rock on a flat surface while the brand new one does not.. Maybe there is a connection between this and the fact that every Justy motor out there has a smoked chain, copper on the bearings or both. I plan to use an anaerobic sealer when I put this on my block. Terry
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Nov 18, 2010 23:46:52 GMT -5
I plan to use an anaerobic sealer when I put this on my block. Now there's a thought. Even if the guide warps later and you get old sealant remnants in your oil it probably won't be that much and will probably just come out with oil changes. You would just need to check your sump every now and then. Sounds like more good than harm. How much did you pay for your guide, if you don't mind my asking??
|
|
|
Post by indkid87 on Nov 18, 2010 23:48:55 GMT -5
Just out of curiosity could you measure the thickness of the bottom flange on the new chain guide to see if it comes to 7.5. When I was looking for a chain guide and trying to figure out which one to pick I measured the bottom flange on my old one. I believe it came out to 6.5 mm so I ordered the white one. Oh and how is that blue?
Dave
|
|
|
Post by Armageddous on Nov 19, 2010 0:34:12 GMT -5
ferox: The sealer I plan to use will take up to .05" gap in a mating surface. I think this should suffice and I wouldn't worry to much about oil contamination with my 4.5l sump. hehe. The guide cost me $71 canadian taxes in. indkid87: All the flanges are exactly the same thickness at 6mm and there is a raised portion near the balance shaft side that measures 8mm. The difference seems to be on the lower left lobe (compare the top two in the first pic) which is the leading edge for the chain. This lobe is where the majority of the chain's force will be transferred. If you look directly in the center of the top guide in the first pic there is a miniature blue dot in the center. Good luck finding that after 100,000+km. Terry
|
|
|
Post by justyjuggler on Nov 19, 2010 10:35:25 GMT -5
|
|
|
Post by indkid87 on Nov 19, 2010 12:53:26 GMT -5
Hmm how did I not notice that, maybe it's meant to take up the slack if your not replacing the chain and sprockets.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Nov 19, 2010 22:24:38 GMT -5
I wouldn't worry to much about oil contamination with my 4.5l sump. Yeah I was thinking more along the lines of flakes of sealant getting caught in the sump intake screen. Because of where the guide is located, if the guide warped and oil pressure pushed out a portion of the cured sealant it would just drop straight into the oil pan without getting chewed up in the grindy engine parts. Cured anaerobic sealant isn't like RTV though, so it's probably not something to worry about anyway.
|
|
|
Post by Armageddous on Nov 20, 2010 1:00:18 GMT -5
Definitely one of those things that could happen, but like you said I'm probably doing more good than harm. The other thing is I plan to use a larger pickup screen when I build my new pickup tube, one with a finer mesh. But for now I will concentrate on getting my motor back together. It snowed today! Terry
|
|
|
Post by Justy1200 on Oct 6, 2011 14:45:27 GMT -5
Hello everybody,
I'm new to this fantastic site. I'm from Switzerland and do run two Justys, built in 1991 (255'000 km) & in 1992 (59'000 km). Half a year ago, the 1991 one has started to make a rattling noise between 2'700 & 3'200 RPM when the engine is delivering strong power, e.g. climbing a uphill. Above 3200 RPM the noise disappears.
I assume it is the balance shaft chain guide which could be worn out. I haven't opened the engine yet. My Subaru dealer was asking me if it's the "white" or the "blue" type chain guide?
In your above statements I couldn't find a final answer to this crucial question. Does anyone have the correct explanation?
Thank you, regards, Rudolf
|
|
|
Post by Armageddous on Oct 6, 2011 21:30:54 GMT -5
Go with blue, it's thicker. I ended up using the blue one on my motor and have not had any issues with it. All me and the parts guy could figure out was that it *might* have something to do with old chain verses new chain. That is, if you replace JUST the guide you should use blue, while if it's all new you should use white. That being said, I used a new chain and a blue guide. Terry
|
|
|
Post by Justy1200 on Oct 7, 2011 10:04:21 GMT -5
Thanks, Terry, thus, I shall order the "white" one, along with a new chain. How probable is the chance that the rattling noise is caused by the worn-out chain guide which never has been changed in 20 years / 255'000 km of operation? Rudolf
|
|
|
Post by Armageddous on Oct 8, 2011 0:16:47 GMT -5
Very likely. In my previous post I showed three guides, you can see the one from the carb motor is worn right down to the aluminum frame. What I didn't show is the damage that chain had done to the inside of the crankcase cover - yikes! Almost wore right through the water passage. I think there is a drastic under evaluation of the chain's responsibility. This chain drives an oil pump and a balance shaft, we're talking serious opposing forces, on a single row chain. Doubled up with the potential to lose oil pressure at the flange, therefor limiting the amount that gets squirted on the chain. Terry
|
|
j
Posts: 1
|
Post by j on Jul 20, 2014 22:20:57 GMT -5
I know this is an older thread, but I have to know if there is a way to adjust the balance shaft chain tension using the chain guide?
|
|
|
Post by Armageddous on Jul 21, 2014 0:24:41 GMT -5
There is no way to adjust it. If there is too much slack, the chain and guide need to be replaced.
Terry
|
|