Totem Posted February 26, 2018 Share Posted February 26, 2018 Well, as some of you may recall I took the plunge and invested in a new custom motor for my rig last year and it fired right up yesterday when I went to see if it would start after the winter days...well I guess its technically still winter but we had nice weather so I thought "why not." The rumble of the motor was raspy and crazy loud. I opened the hood to discover the exhaust is blowing out where the headers connect to the pipe flange and leaking with the exhaust there is HUGE noise. I cannot see how the two plates come together on that union but I am assuming there are some bolt heads that go into the casting and are pointed downward such that the only way one could see them would be staring up through the engine bay from below... anyone see this kind of thing? is this something I can just torque back down? Quote Link to comment Share on other sites More sharing options...
Totem Posted February 26, 2018 Author Share Posted February 26, 2018 * update*, I slipped a mirror under and see one of the studs is gone from the downpipe... Why do I get the feeling I will be fighting this problem over and over and over. gosh dang these things burn hot. Quote Link to comment Share on other sites More sharing options...
WME Posted February 26, 2018 Share Posted February 26, 2018 (edited) FWIW I finally fixed mine, after 3 tries. I got a full set of exhaust gaskets. I removed the header. Installed the gasket. I tightened the manifold/header first, I used Permatex copper rtv gasket on both sides of the header gasket. The 3 bolts got equal torque to make it tight. Next day I reinstalled the manifold to the engine with a new gasket. The theory is the angle of the header is a bit off due the exhaust pipe. The bolts would not get equal torque. Edited February 26, 2018 by WME Quote Link to comment Share on other sites More sharing options...
fred heath Posted February 26, 2018 Share Posted February 26, 2018 I’m not sure I’m following correctly here. As I read your post I understand your attaching the exhaust down pipe to the exhaust manifold first then attaching the exhaust manifold to the cylinder head. This is not a good idea. The exhaust manifold should be securely attached to the head at factory specs then attach the down pipe. To do otherwise will open you to a leak at the exhaust manifold/cylinder head mating surface. The 3 flange studs at the bottom are easily accessible from underneath. Getting the correct gasket is also important. In my case there are 3 different gaskets that could be used for the flange. It’s also important to secure the down pipe to keep it from vibrating which could cause the flange nuts to loosen up. Quote Link to comment Share on other sites More sharing options...
WME Posted February 26, 2018 Share Posted February 26, 2018 (edited) Fred, you read correctly. I tried the "correct" way 2x and the head/manifold would leak after a few trips. As I stated I did this because the manifold had a mismatched angle (new exhaust system). Torquing the bolts resulted in a wedge on the manifold/header flange. By having the manifold off the engine I could get the manifold/header joint perfect. After the RTV set up I mounted the manifold to the engine, the studs in the head kept the manifold correct and I used Permatex copper SPRAY paint on both sides of the manifold gasket. Never had any problems with ether gasket after this. Like I said FWIW, this fixed MY problem If Totem just had a loose nut thats a different problem. Again FWIW never use lock washers on an exhaust. The correct nut is this guy..https://en.wikipedia.org/wiki/Distorted_thread_locknut Edited February 26, 2018 by WME Quote Link to comment Share on other sites More sharing options...
fred heath Posted February 26, 2018 Share Posted February 26, 2018 Glad it worked for you. The only issue for me is you’re now depending on the torque applied to the cylinder head studs to seal the exhaust. There will always be that outward pressure working against you. One thing I do recommend is replace any manifold bolts with studs. It allows you to get even torque around the entire perimeter and negates any chance of stripping the aluminum threads from over torque. I’ve included a picture of my manifold and what the all stud setup looks like. Quote Link to comment Share on other sites More sharing options...
WME Posted February 26, 2018 Share Posted February 26, 2018 Yes I installed studs in the head too. My studs were longer. I see you used brass nuts. Thats works. This is a real old school weird thing, plan old Phillips Milk of Magnesia makes an excellent high temp anti seize. I learned this years ago from a jet engine mechanic. The USAF bought the stuff in 5 gallon drums for use in the hot sections of jet engines. Quote Link to comment Share on other sites More sharing options...
Totem Posted February 27, 2018 Author Share Posted February 27, 2018 In my case its just the down pipe where it meets the exhaust. So far the header on the motor and all is ok. when I crawled under i was missing a stud on down pipe and the other two studs had no nuts pardon the expression...so its basically hanging there leaking. Anyone know off hand what the thread size is on those studs? I want to get the same and same nuts. Quote Link to comment Share on other sites More sharing options...
WME Posted February 27, 2018 Share Posted February 27, 2018 Dorman PN 03105, 2 studs, 2 nuts...$6.29 per set. 10m x 1.25 Dorman should be at any auto parts store Quote Link to comment Share on other sites More sharing options...
Totem Posted February 27, 2018 Author Share Posted February 27, 2018 perfect timing on me lunch break grabbed 6 of them, a doughnut flange and some milk of magnesia. Plan on doubling them up instead of lock washer Quote Link to comment Share on other sites More sharing options...
Maineah Posted February 27, 2018 Share Posted February 27, 2018 That's a Toyota thing that I'll never understand the nuts just rust away and leave nice shiney threads. Have seen several O2 sensors hanging by the wires and others leaking with just a tiny bit of nut left. Seems it's only where flanges are, cats and O2 sensors. 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.