#1
IP: 129.49.200.160
|
||||
|
||||
Basic Metalurgy
There are several bolts, nuts, etc. that will need replacing as I reasemble my engine. I know certain metals, when used together, cause oxidation, or fuse at higher temperatures. What type of bolt should I use: Zinc, Stainless, Other???
|
#2
IP: 76.24.202.79
|
||||
|
||||
engine bolts
It is a mistake to upgrade nuts and bolts on your engine. The danger you alluded to is the galvanic cell. The engine is cast iron, primarily and the bolts and nuts are some grade of carbon steel. Remember, it is the basic castings that are most valuable and should not be endangered by the use of "noble" fasteners. You can probably find a galvanic series somewhere on the internet and note where cast iron lies in the order of things, as it were.
|
#3
IP: 71.130.85.135
|
|||
|
|||
"In my humble opinion"
Matt,
I titled my responce IMHO for a good reason. The subject of fasteners can get as long as we will let it get. Having said this, I generally use grade 5 cad plated bolts for most external assembly accessories. This would include things like the oil pan, the bellhousing, the accessory drive and other similar parts that probably won't be removed for a long time. I install most of these bolts using anti-sieze so that when the time comes to take them out I will actually have a fair chance of doing that. For things like water pumps or the thermostat cover it is not a bad idea to spring for stainless along with anti-sieze to insure that the bolts or nuts will stay as fresh as possible. In the case of the accessory drive mounted water pump, using one of Don's SS extendo bolts in the lower hole will make pulling that part off a snap. I could go on and on but I won't. Bottom line, every time you install a nut or bolt just keep in mind that it will probably have to come back sometime. Hope this helps, Tom |
04-27-2010, 03:36 PM |
FelicityRebuild |
This message has been deleted by FelicityRebuild.
|
#4
IP: 76.24.202.79
|
||||
|
||||
As long as we let it...
As you can see from the previous two posts, there is considerable range of opinion on this matter of fasteners. Note, however, that Thatch and I seem to concur on the use of some sort of steel for oil pan, housings, etc - things with the greatest liklihood of contact with some sort of water or bilge splashing. As you will see, the galvanic cell only occurs in the presence of an electrolyte (salt water, or any ionized water for that matter). You could bolt graphite to aluminum and as long as you kept it dry, there would be no problem(But remember the jet liner over Kennedy International Airport that lost its tailfeathers - aircraft fly in salt conditions too). It would seem, however, that in the case of the A4 some locations in the engine room would be less susceptible to "salt mist" - say, the lower water pump bolt. In fact a little oil leak in this area could do a lot to protect the metal. Having antifreeze cooling goes a long way toward mitigating this issue. If I were using salt water cooling, I positively would not put stainless fasteners near that thermostat housing. Finally, a word on the use of metallic based "never seize" type of products. Although it is satisfying to be able to disassemble an engine easily, may it not be at the price of deteriorated bolts and castings. Read the label. I'm sure that if this thread continues (someone is certain to jump on me) you will see that where 25 A4 owners get together, you will get at least 50 opinions. All the best to you and keep us posted!
|
#5
IP: 69.237.146.217
|
|||
|
|||
"More thread on threads"
hanleyclifford,
Since I consider myself a nut and bolt "commoner" when it comes to the "noble" chart I'll defer to others who actually stayed awake in science class to cover that part of the discussion. You and I both mentioned a particular bolt which gave me a chuckle and I'll explain why. Not long after acquiring my A4 equipped Catalina 30, I spent about 30 minutes lying on my side with hammer and drift in hand trying to coax a little rotation out of the now infamous lower water pump bolt. The bolt head over the years, because of leaky seals and improper tool techniques, had been reduced to a round nub. Finally, after a successful effort, I was able to remove the pump, rebuild it and re-install it using my own version of the extendo-bolt. Cordially, Tom |
#6
IP: 75.5.234.204
|
||||
|
||||
Tom, what is your own version of the extended bolt?
|
#7
IP: 98.217.114.66
|
||||
|
||||
nuts and bolts
Quote:
|
#8
IP: 71.129.172.181
|
|||
|
|||
Re: marthur question
Mike,
Thank's for asking. My version of the bottom water pump bolt is nothing more than a 3/8" coarse thread SS hex head bolt 4" long on to which I have firmly bottomed out a 3/8" SS nut. The nut now becomes what was the head of the bolt in the old system with the majority of the new bolt now allowed to extend slightly beyond the water pump cover. The threads left exposed are about 7/8" long which is just about perfect considering the thickness of the WP flange and the thickness of the accessory drive in that area. Just in case you're wondering, the two WP mounting holes are positioned to miss the idler and accessory drive gears, if someone were to install a bolt that was longer than needed. Tom |
#9
IP: 206.125.176.3
|
||||
|
||||
awesome
Tom,
Brilliantly simple!
__________________
-Shawn "Holiday" - '89 Alura 35 #109 "Twice Around" - '77 C-30, #511 with original A-4 & MMI manifold - SOLD! (no longer a two boat owner!!) |
#10
IP: 71.130.130.55
|
|||
|
|||
I belong in jail!
Shawn,
Don should get all of the credit for the "long bolt concept. I should only get credit for stealing his idea. |
#11
IP: 64.231.104.181
|
||||
|
||||
Quote:
I would be very cautious with this one fellows and measure the length of the threaded portion of the housing before installing a "home-made" extended bolt. Cheers! Last edited by 67c&ccorv; 04-28-2010 at 09:37 PM. |
#12
IP: 71.130.87.31
|
|||
|
|||
sorry to have to disagree
67c&ccorv,
Before I gave my answer to marthur I went through the process of mocking up the components involved. These parts are the idler gear, the water pump and the accessory drive unit. After carefully checking for any possibility of bolt interference it was obvious to me that Universal was very careful to make sure that a longer bolt than necessary could not contact the gears. After your post, I recreated my mock up but this time I used all thread and ran it in until it bottomed out on the housing on the opposite side. I'm sure you know the answer by now, no interference at all. I did find your post on this subject and I think if you look at the photo a little closer and visualize the position of the accessory drive gear, you will see how the bolts will clear. Tom |
#13
IP: 64.231.104.181
|
||||
|
||||
Quote:
I won't go so far as to say the block and associated castings are "stainless steel", but they are certainly not the kind of pot steel one would find in a automobile engine. I would say if you want to improve your fasteners with S/S and are worried about galvanic corrosion then use blue loctite (which can be removed with hand tools) which will form a barrier between the threads or body of the fastener and surrounding engine components. |
#14
IP: 76.24.202.79
|
||||
|
||||
Claims by Universal of "high nickel-chromium" notwithstanding, the empirical evidence clearly shows that these engines are highly subject to corrosion in the marine environment, both galvanic and otherwise. The engine castings are indeed mostly ferrous - containing alloys of nickel and chromium, but not enough to move them up significantly on the galvanic series so that they might be electrochemically immune from attack by more noble metals!
|
#15
IP: 64.231.104.181
|
||||
|
||||
Quote:
Just don't be bodgers! |
#16
IP: 71.130.106.234
|
|||
|
|||
67c&ccorv,
Thank's for your responce. You are perfectly correct in saying that we should always be careful to use the correct length fasteners. I have run accross cases (on other types of engines) where you could actually crack a cylinder wall by using a bolt that was too long. The word "Bodger" was new to me and since I was unable to find it in my dictionary I decided to do an internet search on it. The best I could come up with was that it was a name given to "highly skilled itinerant wood workers in a small town between Oxford and London", so I guess I will take it as a compliment.... Now, Botcher, that's another story completely. Regards, Tom |
#17
IP: 64.231.104.181
|
||||
|
||||
Quote:
Unless you want to cast in in bronze or titanium (or unobtanium) there is no steel that will not eventually corrode - it is just a matter of how fast and how long. Whatever the composition of the castings Universal used/was(?) I would suggest it goes a long way to explaining why nearly one half of the 20,000+ engines built are still operating. Some, (as in my case) still with the original block and castings from the 1960's and earlier. |
#18
IP: 24.152.140.113
|
||||
|
||||
Do I interpret this to mean we can expect dissimilar metals issues between stainless and iron to be minor, or easily mitigated with something like anti-seize?
__________________
Neil 1977 Catalina 30 San Pedro, California prior boats 1987 Westsail 32, 1970 Catalina 22 Had my hands in a few others |
#19
IP: 98.217.114.66
|
||||
|
||||
dissimilar metals
It is well established in the (especially) wooden boat building and repair business that issues of dissimilar metals are NOT minor and galvanic corrosion can be startlingly rapid in some instances. Look at the wood and note the stringy yellow fibres near the offending cell, as well as the white or blue powder near the cathode. What determines the intensity of the cell is the degree of dissimilarity of the metals. This is why we always consult the galvanic series chart before using two metals in proximity. The stringy yellow fibres are the result of what is called electromagnetic delignification at the cathode. Of course in metal the destruction is the result of the noble metal stealing electrons from the less noble. In the case of an engine block just about anything is going to be "more noble" except for the useless stuff like aluminum etc. Tom uses capscews plated with cadmium; the cadmium is anodic in this case and should in fact to some extent "take the galvanic hit". Stainless steel at a location like, say, the oil pan would be deadly because it would tend to steal electrons from the casting even an alloyed one, albeit at a lesser rate than one of straight "pot" iron. As far as the use of antiseize products is concerned, I don't use them. Read the label and see what a mini self contained little galvanic battery it has the potential to be.
|
#20
IP: 24.189.230.251
|
||||
|
||||
ok. I love that my first two questions I ask this panel have sparked (almost) heated debate. Between this discussion and the question I posed about the valve guides, It's been very educational. I was warned that I may get 50 people giving me 100 different answers. I can handle that. I've learned in my life to listen to all perspectives then make my own decision. I appreciate all of your help and I thrive on scientific discussions such as these. However. I'm still at a loss as to what type of metals to use for replacement bolts. Does MMI have a standard type they use? Do they discern between an oil pan bolt or a bolt that goes on the transmission cover, or do they use the same type for all? Maybe there is no answer. I do realize that that's a possibility. If that's the case, I'll simply make a note of the bolts I replace and keep a very close eye on them. I'm ok with that option too.
|
#21
IP: 24.152.140.113
|
||||
|
||||
Quote:
Yet the Moyer Marine water jacket side plate bolt repair kit is all stainless! ref: (CSOT_04_307)
__________________
Neil 1977 Catalina 30 San Pedro, California prior boats 1987 Westsail 32, 1970 Catalina 22 Had my hands in a few others |
#22
IP: 76.24.202.79
|
||||
|
||||
nuts and bolts
You will never go wrong using the grade 5 medium carbon steel, with the cadmium plating (like Thatch) if you want a little anodic protection. Many special fasteners are listed in the online MM catalogue. The grade 8 is nice too if you can spring a little extra $. Definitely check the catalogue first.
|
#23
IP: 76.24.202.79
|
||||
|
||||
Another strong argument to have a top quality antifreeze cooling system!
|
#24
IP: 76.24.202.79
|
||||
|
||||
One more point on the MM repair kit. This item actually replaces the original threads in the casting with a "thru bolted" unit. It is threads that are most vulnerable to galvanic "assault". Once installed the repair kit sets up along its entire length against the casting thus spreading the connection against a much more substantial metal surface. In an antifreeze environment, other things being normal, I might start looking for trouble from this installation after around 50 years.
|
#25
IP: 71.133.6.6
|
|||
|
|||
It's all your fault, Felicity!
In order to keep this thread spinning out of control I'll throw another little thought into the mix. During my current A4 rebuild on my spare motor and on other engines where strength is not an issue I use brass. In the case of the A4, the brass will be studs locktighted (red) into the block and I will use brass washers and nuts to hold the parts in place. The 3 particular parts that will get this treatment are the transmission cover, the block side cover(water) and the 2 carburator mounting studs. Brass seems to about the least offensive of the non corrosive type of metals, and dosen't gall. The use of studs does a couple of things that I like, they save wear and tear on the threads in the block or manifold and and I find it easier to line up the parts for reassembly. Red locktite holds better in these cases like these and a little heat will loosten them up if you have to remove them. Any thoughts?
Tom |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
basic parts | anhinsb | General Maintenance | 9 | 08-19-2009 10:28 AM |
basic maintenance questions | anhinsb | General Maintenance | 8 | 06-18-2009 02:35 PM |
New member, basic questions | Andy Gump | Introductions | 2 | 04-13-2009 05:22 PM |
Basic Information on the Atomic 4. | Hazelnut | General Interest | 0 | 09-05-2007 11:15 AM |
Basic Question: Stud installation | timday5 | General Maintenance | 2 | 08-04-2007 11:11 AM |