Hello! I'm in the process of replacing a leaky fuel pump. Had a question about the torque specs of the crush washers in the photo. Not sure if A, B, and C have the same torque requirements? Thanks in advance for any guidance!! Image Unavailable, Please Login
Just "crush" it a bit. tighten the bolt/nut until it bottoms firmly on the washer and give it another 1/4 turn. That will be sufficient. FWIW, if you are dealing with a COPPER crush washer and can't find the right one (or don't feel like going to the parts store), you can anneal/reuse the old one. I have reused some copper oil pan crush washers 4-5 times. Heck, I have one on a Norton Commando motorcycle that hasn't been replaced with a new one since 2006!
You can also anneal aluminum crush washers. I had an Acura for 10 years that had an aluminum crush washer on its engine oil drain plug. It was used over and over with never a leak. Ditto for the 5 series BMW that replaced it. I've never bought these washers, either copper or aluminum. Just got through changing the transmission oil on my '87 GTS. Annealed the old washers and reused them. Can't remember how many times I've reused the washer on my 328's engine oil drain plug and Porsche track car's engine oil plug. But I do not own a business fixing cars. If I did, I'd use new washers. If one of my vehicles starts dripping oil at the plug, then it's time to buy a new washer. But it has not happened yet.
In my experience there's actually more chance of a new Copper washer leaking unless it's also annealed. I'm sure the Copper content of the average washer has decreased over the years, just like cheap Chinese copper pipe.
Do you suppose when auto factories build new cars they anneal the copper washers? I am pretty sure they do not. I install sometimes 100 new crush washers in a week and have never annealed one. If you do things the way auto builders do you wont have a problem. If it didn't work, they wouldn't do it.
"If you do things the way auto builders do you wont have a problem. If it didn't work, they wouldn't do it." I don't know about that, Brian.... Ferrari installed an air conditioner system that didn't work for the entire 3x8 production run! In any case, I agree - I can't imagine that any engine manufacturer anneals their copper washers before install. Re post #6...I was not aware that aluminum (washers) can be annealed in reasonable time/with typical tools. Copper, you just heat till red hot and allow to cool - takes maybe 5 minutes from start to finish, heating with a propane torch. From what I understand, AL requires a specific temp (higher than a home oven can achieve) based on the particular alloy and it has to be held at that temp for up to several hours. Is that not correct?
What I always did with aluminum was to take a lit candle and hold it under the aluminum washer allowing soot to collect on the aluminum. Then take a propane torch and carefully heat the aluminum until the soot disappears. Then quench it. Another way I have heard about but have not ever tried (because I don't have the Acura) is to take a Sharpie and 'paint' the aluminum. Then heat the aluminum until the 'paint' disappears. use sharpie to anneal aluminum - Google Search
If you can control it, tighten the copper washer "C" under the banjo a bit more. Upon disassembly one day the banjo (A&B) should come loose before the bolt. A and B will always receive the same torque - by the same nut. Am I making sense? I did find horrendous torque values for those fitting on the web, directly related to the thread dimensions. As in 100 Nm (65 lbft) like for a 7/16 UNF cylinder head bolt!
Because I can. During my career in the chemical industry, two people in the same section were metallurgists who held graduate degrees in metallurgy. And they said I could. It takes about 10 seconds to heat a copper seal and quench it. I began doing this in the early 1980's when I bought my 1980 Benz. I've been doing this for 40 years on various vehicles. Do what makes you comfortable. But don't tighten copper seals until they spread out like pancake batter on a griddle.
Try, for example, fitting a Triumph motorcycle aftermarket (L J Harris) brake master cylinder and /or reservoir without any of the three banjo bolt washers leaking, unless the supplied Copper washers are first annealed. It's almost impossible. Cheap washers can get hardened during the punching process, and I think this is the problem. After several experiences like this, I, personally, anneal new washers. If I had visibility of the washer spec's that I bought, then I would probably be more inclined to use them as bought. Unfortunately, unlike car manufacturers, I don't have a pool of people checking the composition against claimed specs of parts like this, of thing I buy. So I will never be able to do it like a car manufacturer, hence my decision to anneal them.
Funny, I could have sworn the topic was a Bosch fuel pump in a 328. Not some POS British junk. Still a stupid decision.
Back in mechanical school, in hydraulics we were teached to tight regular NEW fittings to snug contact + 1/8 of a turn and USED + 1/16. Check for leaks and slowly tight if any leaks to reasonable torque. If not correct replace.
There's actually a lot going on here and some key differences. Tightening the nipple fitting onto the pump body with washer "C" you're both compressing the washer and shearing it with rotation. That one you would hand tighten to contact then snug until you feel it slip and build resistance. The slip feels almost like stripping threads so it may be a familiar feeling (years ago I stripped hundreds of bolts for QC testing and know it all too well). That washer is thicker because it is meant to take more oomph while sealing the fitting connection. When tightening the cap over the banjo, washer A will experience compression and shearing, while B will only experience compression. These are thin and that indicates they are mainly acting like a gasket and working by compression. Won't take too much to snug these down. I think it's admirable folks try to reuse washers and relieve internal stresses with annealing, but annealing won't reverse the deformation that happens during the crushing/shearing process. Copper doesn't have shape memory. At some point that washer will have deformed enough that I wouldn't trust it.
