rayaapp2 Posted October 28, 2012 Share Posted October 28, 2012 So I just had a head cleaned and surfaced and Ive found that the front right head bolt near the coolant passage has corrosion that has broke through to the head bolt passage. Its been that way for a while, but now Im worried it wont seal now that Ive disturbed it by cleaning it. The passage will definitely fill with coolant now. I think that area can be drilled and a competent tig welder could in theory fill it back up so that it could be re-drilled and re-surfaced. Im worried though that if I go that route with a repair that the head will not be repairable. If I leave it as is Im worried the coolant system could loose pressure at that head bolt passage or in the least corrode the head bolt. Another option I guess would be to drill the bolt passage and press a sleeve into it as a band aid. The coolant passage has corroded through about .75" up the hole from the gasket surface. Ray Quote Link to comment Share on other sites More sharing options...
Xnke Posted October 28, 2012 Share Posted October 28, 2012 (edited) Those early heads are a PITA to weld on; ESPECIALLY when they have been corroded by coolant. Contaminated tungsten and weld porosity are the rules of that particular game, and there is only one way to fix either problem...grind it back and try again. I'd suggest 4047 rod, instead of the more common 4043 alloy, specifically for the porosity issue. It can be a job-saver on castings or contaminated aluminium. The only repair I'd make there is to gouge the head out all the way into the water jackets, weld it back solid, then re-machine the head bolt hole and the water passage hole. Then surface the head. I would charge probably 300$ for that kind of repair work; and I'd STILL probably be cutting it close on margins. Yes, since buying my TIG welder I've done more aluminium cylinder head repair than anything else. If I am imagining your problem correctly, the two paths that could be taken to get down in the hole both really suck. One is to literally chop your way in, and weld your way back out. This takes a lot of time, argon, and rod. The other method would be to use a long-series cup, a gas diffuser, and work blind down in a hole. This is risky, even for very experienced welders, because each layer of weld needs to go in right..one bad weld in the stack and you're back to square one...gouge it out and start over. I currently have a cylinder head in my floor that is for a different engine, (actually cut two heads and welded them together to make a head for a bigger inline-six) with a very similar problem...the only solution I have there is to gouge the whole head-bolt boss off and then weld the head back solid, working back out from the inside. But if you do that, where ELSE has the water jacket breached the head? That's a particularly thin area, but it's no thinner than a few other areas on the head. No point in working a corroded up cylinder head if you don't have to, is the point I'm trying to make. Edited October 28, 2012 by Xnke Quote Link to comment Share on other sites More sharing options...
rayaapp2 Posted October 29, 2012 Author Share Posted October 29, 2012 hmm, Ill have a closer look at the head and see if I can find any other hidden flaws. Your probably right. I do like my idea of sleeving the bore for the bolt though. A stainless sleeve would do the job nicely. Im going to take the head back into the machine shop and see what he says. He works on a lot of Datsun engines so he may have an idea or two as well. Quote Link to comment Share on other sites More sharing options...
Xnke Posted October 29, 2012 Share Posted October 29, 2012 Stainless and aluminum do not mix well when it comes to corrosion. Also, once that stainless sleeve is in there, it won't expand and contract at the same rate the aluminum head will...which will cause scrubbing between them. It will seep water. Quote Link to comment Share on other sites More sharing options...
Tony D Posted October 29, 2012 Share Posted October 29, 2012 Aluminium sleeve shrunk with LIN, pressed into a 200F head with a loc title covering will be permanent. And steel inserts have been used under head bolts on the L-Engine for decades, but it's not the right application for what you need. Quote Link to comment Share on other sites More sharing options...
johnc Posted October 29, 2012 Share Posted October 29, 2012 Yeah, boring the head bolt hole and sleeving it will probably be the best option. Hi-Temp Lab Metal would be a good alternative to Loctite to hold the sleeve in place. It might also be an option all by itself to repair the bolt bore. Quote Link to comment Share on other sites More sharing options...
rayaapp2 Posted October 30, 2012 Author Share Posted October 30, 2012 The local Machine shop that works on Datsun L series all the time(4 in there at the moment too) quoted me $125 to gouge out the whole area and fill it back in. Another $80 to re-drill and surface it. Sounds like a hell of deal to me. I did have a good look at all the other passages and they all have plenty of meat left in them strangely. It must have just been a badly cast area or something along those lines. Thanks for all the input, Ray Quote Link to comment Share on other sites More sharing options...
Xnke Posted October 30, 2012 Share Posted October 30, 2012 That's a great price on that kind of work. Either he's really good, or he's got a plan, ya know how that is. Let us know how it turns out. Quote Link to comment Share on other sites More sharing options...
rayaapp2 Posted November 2, 2012 Author Share Posted November 2, 2012 That's a great price on that kind of work. Either he's really good, or he's got a plan, ya know how that is. Let us know how it turns out. Apparently this kind of work on these heads is common for him. He already knew what rod he needed to work with. Im very thankful to have local machinists that know what an L-series is and still work on them! I will post back with the results. Quote Link to comment Share on other sites More sharing options...
Leon Posted November 2, 2012 Share Posted November 2, 2012 Ray, What shop are you using? Quote Link to comment Share on other sites More sharing options...
rayaapp2 Posted November 3, 2012 Author Share Posted November 3, 2012 Schroeders in Seaside Ca. Quote Link to comment Share on other sites More sharing options...
Leon Posted November 5, 2012 Share Posted November 5, 2012 Schroeders in Seaside Ca. Good to know, thanks! Quote Link to comment Share on other sites More sharing options...
rayaapp2 Posted November 17, 2012 Author Share Posted November 17, 2012 Cylinder head is back and looks good. The total thickness of the head is now 106.9mm vs spec of 107.9mm. Im tossing the idea of 1mm tower shims. Thats what almost .040" of an inch missing. Im guessing I will need shims. Im going to forget about gasket crush at the moment and see what the cam timing looks like a little later tonight. I was hoping to spend my weekend assembling and installing the engine into the car, but if I have to order cam tower shims that puts me out another week. Quote Link to comment Share on other sites More sharing options...
Xnke Posted November 17, 2012 Share Posted November 17, 2012 Shims come in 0.015" thicknesses, or 0.020" thicknesses, depending on who you buy from. Silver Seal has them listed on their website. Quote Link to comment Share on other sites More sharing options...
Tony D Posted November 17, 2012 Share Posted November 17, 2012 1mm=0.040" Quote Link to comment Share on other sites More sharing options...
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