XTCoX Posted August 21, 2009 Share Posted August 21, 2009 Well, I'm stumped. We just replaced the head gasket, head, and everything else that connects to the head, and this engine is billowing steam out the tailpipe. Could the water jacket be busted in the head? The head had been restored to a clean, polished finish, with all reconditioned equipment. The only explanation I could come up with was that the water jacket was cracked somewhere. Anybody have any other idea's what's going on here? Quote Link to comment Share on other sites More sharing options...
Meph Posted August 21, 2009 Share Posted August 21, 2009 did you check compression with the new HG to make sure its alright and not leakin? Its possible theres a crack in the head/block i would think Quote Link to comment Share on other sites More sharing options...
MAG58 Posted August 21, 2009 Share Posted August 21, 2009 Before you put it on did you have the head pressure checked? I bought two P79 heads off running cars, both ended up having cracks in the water jacket. Quote Link to comment Share on other sites More sharing options...
Phlebmaster Posted August 21, 2009 Share Posted August 21, 2009 A buddy of mine had this similar problem...it turned out to be the head. Quote Link to comment Share on other sites More sharing options...
XTCoX Posted August 21, 2009 Author Share Posted August 21, 2009 No, I didn't do a pressure check personally, but they guy we bought it from said he did. I guess you can't trust anyone. Anyway it's good to know that this is a common problem...now I can stop feeling like the world is ending . Thanks guys. I'm getting an E31 with a stage 3 cam, heavy machine work and N42 valves tomorrow. That's going to be fun. Quote Link to comment Share on other sites More sharing options...
jasper Posted August 21, 2009 Share Posted August 21, 2009 Did you run it LONG ENOUGH to clear out the exhaust system from the previous failure????? This could possibly take quite a while. I've been in this situation before. Quote Link to comment Share on other sites More sharing options...
zcarnut Posted August 22, 2009 Share Posted August 22, 2009 Did you run it LONG ENOUGH to clear out the exhaust system from the previous failure?????This could possibly take quite a while. I've been in this situation before. Same thing happened to me as well. Jasper's right. Let the engine run for at least 30 min. Quote Link to comment Share on other sites More sharing options...
XTCoX Posted August 22, 2009 Author Share Posted August 22, 2009 how much water could accumulate in the system that it would take 30 min to clear out? Im not disagreeing, just a little surprised that it would take that long to clear out. There was steam billowing out of the exhaust, when we revved it, when it idled....you're saying that this could be just from accumulation alone? Ill give it a shot, but that seems like it would have to be a liter or so of fluid stuck in the exhaust for that much steam to be coming out of the tailpipe. Quote Link to comment Share on other sites More sharing options...
XTCoX Posted August 23, 2009 Author Share Posted August 23, 2009 Got the E31 on today. Runs like a champ with the Stage 3 MSA cam in it. No more steam either. Side question for you guys: There was some extensive machine work on the head, which included a new 3-angle grind, and 280z valves. So, how do we know when the valves are properly seated? 50 miles or so? Quote Link to comment Share on other sites More sharing options...
MAG58 Posted August 23, 2009 Share Posted August 23, 2009 If they were lapped, they should already be properly seated. When you start to get lots of popping back through the intake or backfiring, I can tell you they're not properly seated. Quote Link to comment Share on other sites More sharing options...
XTCoX Posted August 23, 2009 Author Share Posted August 23, 2009 Well, Im not getting any backfiring or popping, so that's good news .... But that term you used...Lapping...Im not sure im familiar with that one. Sorry for the ignorance, I've just been on a car-rebuild-crash-course for the past couple of days. The guy that we bought the head from said that we had to keep it under 3000 rpms for the first 50 miles or so, bcause "the valves weren't properly seated yet"...Is that correct? Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted August 23, 2009 Administrators Share Posted August 23, 2009 The parts that require break-in to seat themselves are the piston rings to the cylinder walls and the cam lobes to the lifters/rockers. All the other parts should be good to go from the initial start up! Quote Link to comment Share on other sites More sharing options...
zedsn Posted August 23, 2009 Share Posted August 23, 2009 Did your vapor problem go away after awhile? If not try retorquing the head. Quote Link to comment Share on other sites More sharing options...
MAG58 Posted August 23, 2009 Share Posted August 23, 2009 Lapping refers to "hand seating" the valves if you will. A lapping compound (basically grease with some grit mixed in) is applied to either the seat or the valve, then the valve is inserted and spun against the face. In doing so, the lapping compound makes a small 'cut' if you will on both the valve face and seat ensuring that both have 360 degrees of contact and the best possible sealing. Quote Link to comment Share on other sites More sharing options...
XTCoX Posted August 23, 2009 Author Share Posted August 23, 2009 thanks for the info Bob . BRAAP, the piston rings are far from new, so those don't need the break in, but a reground cam and reconditioned rocker arms would. So how long before they are broken in? zedsn, the vapor problem went away. Thanks for the quick response guys. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.