MGB Exhaust rubbing on steering column 77 MGB

[Simon Hughes]

I'm in the middle of replacing the exhaust manifold gasket and have run into some issues. Good news is that I searched the forum and found some suggestions forremoving my broken stud/thread stripped, and lack of room to get the manifold past the studs (remove the studs & replace).

I noticed that my exhaust down pipe is touching the steering column. Doesn't seem right to me even though it's only a slight touch. Rust ring around the steerring column suggests it's been like this for a while. No wear marks though.

Any suggestions on how to create a bit more space? There doesn't seem like there can be much as the other side of the downpipe is already touching the side of the engine.

Thanks.

Simon

 

[JPSmit]

Any suggestions on how to create a bit more space?

Thanks.

Simon

:grin:

 

[DrEntropy]

Check the motor mounts.

 

[PAUL161]

I agree with Doc! You have the round mounts and if the front mounts are shot, they will let the engine drop down a bit, possibly causing your problem. If the left mount is worse than the right, it will let the engine shift slightly to the left and visa versa. If the car isn't bent, then it has to be the mounts. JMHO. PJ

 

[Simon Hughes]

Thanks JP, I did think about that. I guess I'll check the motor mounts first though.

Thanks for the suggestions.

 

[PAUL161]

Simon, One thing I didn't think about is, does your car have the stock exhaust system on it? Over the years a lot of these cars have been tinkered with so much that you never know what your going to find until you dig deeper into the cars workings. Strange things pop up at times. So don't think your alone, just study the situation and take it from there. If you have a friend who knows MGs, ask him to look at it for you. Amazing what a knowledgeable person can find. Forums like this one are a gift. You could not count the years of knowledge that abounds here. PJ

 

[RoMo]

The bonded mounting plate can become unattached at the bottom and allow the engine to move down a little and contact the exhaust also someone may have forgotten to replace the mounting metal spacer when the engine was last installed. There is no part number xxx for this component in Moss parts list so you will have to obtain it from a breakers-yard or E-bay. To check:- place plywood packing under the oil pan and jack up the motoand check the rubber mtg

 

[PAUL161]

Late model shims ARE available through Moss! Part number 413-062 at $1.95 per shim. Use as many as required. No one can determine the amount needed without lifting the engine to it proper position and measuring the gap after the new mounts are installed. I would buy 4, their cheap and it shouldn't take anymore than that. If you don't need them, your not out much money. PJ

 

[Simon Hughes]

It looks like the exhaust system has been swapped out for something called a 'short exhaust header' https://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=44026

It's not obvious that the engine has dropped but I'll certainly take a look at that.

As an update, I managed to get the old exhaust studs out. 1 nut stripped the thread so I cut it off. Latest issue is that one new stud won't go back in. Looks like the thread in the cylinder head is damaged.
Anyone have any tricks to fix that other than tapping a new thread?

Thanks.

 

[PAUL161]

Simon, If the threads are to a point that a thread chaser will do no good, I'd get a heli-coil kit for those stud sizes, which comes with the appropriate size drill bit and tap, carefully drill out the hole, run the tap in and install the coil. The kit comes with the coil insertion tool as well. That way you keep the proper size stud and threads. I had to do that on my bell housing bolts on the TF, as half of those were stripped out. Works very well. Heli-Coil brand is top shelf in my book. PJ

 

[DrEntropy]

Heli-coil it. Keep everything as uniform as possible.

 

[DentonPerry]

Photo?

 

[Simon Hughes]

Hi gents, update and an ask. I got the thread cleaned out with a brand new tap/die set. Replacement stud went in a treat.

All back together started up fine but still really noisy and lots of smoke. I've now worked out that the carb manifold & exhaust flange are different thicknesses so I'm not getting a good seal to the head gasket around the manifold studs. I've read through a few messages and there are suggestions around fitting manifold shims to level things up.

Any suggestions on how to make up some shims? Can you buy them?

 

[PAUL161]

Someone makes those step washers, but I can't remember who. You can make your own by cutting a proper thickness washer in half and tack welding it to the original thick washer. This is usually a problem when installing an after market item along side an original, such as original intake and after market exhaust or other way around. The thickness is usually different between the two. PJ

 

[CZ_Dave]

You can always go to Fastenal
or to the Home Desperate or
Lowes hardware dept and
get washers to shim the nuts to
the right depth so that the intake mounts properly.

 

[PAUL161]

Dave, I don't think Simon has a problem with shimming the nuts, it's the two different levels between the intake and the exhaust where one stud goes between and the washers will not level out to get an even surface and pressure for the nut to set on and torque up. I had this issue on a 79 with a Weber manifold on it and had to make step washers that rest evenly against the intake manifold and exhaust manifold. The intake was 5/8' thick and the exhaust manifold 1/4' thick. Just sayin. PJ

 

[Simon Hughes]

Hi PJ, yes that's exactly correct. I don't have the tools to accurately measure but it looks like a 4-5mm difference. To make matters worse, it looks like a previous owner has welded some shims onto the exhaust but only on the bottom half meaning I don't have an even surface to work with on the exhaust. I'm guessing this has existed for a long time.

I'll try to take some photos tonight and share.

 

[Simon Hughes]

Hi guys, here's a picture of the different levels between exhaust and intake manifold. I made up some shims/spacers and tightened everything up but it looks like I'm not getting a seal as the bottom of the intake is hitting the top of the middle downpipe. How much of a gap should there be between manifold & pipe?


Also, if I swap out the exhaust for an original would the levels be the same? In other words, is this issue I'm having a function of the exhaust system?

Thanks

 

[PAUL161]

Simon, I didn't notice, do you have a stock intake or is it a Weber? PJ

 

[Simon Hughes]

Stock as far as I can tell.