Intake Backfire:Doing intake & exhaust gasket Exhaust stud busted off flush w/ head

[5thhorsemann]

http://www.mcmaster.com/#drill-jig-bushing-liners/=f7ebbd

http://www.mcmaster.com/#end-mills/=f7eeqb

http://www.mcmaster.com/#thread-repair-inserts/=f7egtq

If you use the mating part (manifold) to fabricate a template out of 1/2 inch aluminum stock that bolts to the good fasteners and place the hardened bushing in the hole for the broken or stripped fastener, you will get a really accurate repair. You can use this method to fix the crooked or offset hole you made trying to work around the distributor, just use an endmill instead of the drill bit. I would use a drill press to get the template set up to increase the straitness of the alignment bushing.

[FastWoman]

Nice jigs!

Horseman, I hope my studs don't back out! I actually talked this issue around a bit before using the antisieze on the studs. Opinions were mixed; however, my own take-away was that the steel/aluminum corrosion would hold the studs in place quite well, while the antisieze, applied sparingly, would keep the corrosion from developing to the extent that the stud couldn't be removed.

Now, in your 350, you would have been using the antisieze for steel-to-steel, so you wouldn't have had the corrosion to cement your bolts into place. FAIW, I've used antisieze sparingly on my saltwater cooled 318 Marine inboard (manifolds, transmission, alternator, fresh water pump, etc., and I've not yet had a fastener back out. The antisieze seems to strike a nice balance between salt-induced corrosion and lubrication. I don't have a particularly long track record with antisieze on this engine, but so far, so good.

[5thhorsemann]

I applied the nickel-never seize only to the three leading threads and used a torque wrench to set the bolts. Steel on steel, agreed. But I'm not relying on corrosion to hold a mechanical fastener in place on anything, least of all a motor.

Also keep in mind that threads lubricated with never seize will give you a smother and more accurate torque value, so stay at the middle or lower end of the recommended torque range for that connection to avoid damaging the hardware.

It has been my experience/ observation, that overtorquing a steel thread against an aluminum thread is at the heart of most broken bolts and studs. I'm not sure if the heat developed during torquing causes the gauling of the threads, or the overtorquing causes the softer thread to crack and deform causing the gauling. I do know that if you prep every female thread with a tap and every male thread with a die and torque the hardware appropriately, you will eliminate 99% of the potential problems that cause the fastener breakage in the future,

Besides, if you read the OP, the stud was broken during the installation of the manifolds, which means the part was overtorqued and likely destroyed the aluminum threads before the steel snapped. This is just a result of bad practices by the mechanic

.

[Ben's Z]

Actually the steel broke before the aluminum threads put out or stripped. Turns out my Dorman, part does not fit. I already contacted the product manager about it....

I applied the nickel-never seize only to the three leading threads and used a torque wrench to set the bolts. Steel on steel, agreed. But I'm not relying on corrosion to hold a mechanical fastener in place on anything, least of all a motor.

Also keep in mind that threads lubricated with never seize will give you a smother and more accurate torque value, so stay at the middle or lower end of the recommended torque range for that connection to avoid damaging the hardware.

It has been my experience/ observation, that overtorquing a steel thread against an aluminum thread is at the heart of most broken bolts and studs. I'm not sure if the heat developed during torquing causes the gauling of the threads, or the overtorquing causes the softer thread to crack and deform causing the gauling. I do know that if you prep every female thread with a tap and every male thread with a die and torque the hardware appropriately, you will eliminate 99% of the potential problems that cause the fastener breakage in the future,

Besides, if you read the OP, the stud was broken during the installation of the manifolds, which means the part was overtorqued and likely destroyed the aluminum threads before the steel snapped. This is just a result of bad practices by the mechanic

.

[Ben's Z]

I have put in the heli-coil...Anyone use locking nuts with a shoulder on them instead of using the washers that go between the nut and exhaust manifold? I dipped the studs in chemdip and cleaned them up pretty good, so I plan on reusing them. I do need new nuts though.

[Zed Head]

I think that the spherical shape of the stock "washers" is designed to take up any thickness differences and equalize the load between the intake and exhaust manifold flanges. A flat surfaced shoulder bolt will only put pressure on the highest surface, plus it will put a bending load on the bolt if there is a thickness mismatch. Might work if both flanges at every location are of the same thickness.

[5thhorsemann]

As I recall the original washers are sprung (dished) to compensate for heat expansion as well. I would (did) order a new set. they're all over ebay and the local dealer had them as well. Cheap enough to go stock on this one.

[Willoughby Z]

And to add to 5th's valid comments regarding the use of anti-sieze/ torque specs- engineered applications of hardware, ie washers vs flange nuts, have an effect on torque. That is, a nut "slips', if you will, on a washer whereas there will be greater friction or resistance between the flange nut and the mating surface. Where torque specs are important, the hardware should be correct to the original design or at least compensated for.

[Ben's Z]

OK finished! I had to have the exhaust manifold milled down because the #5 runner had literally a divot missing from the face from the exhaust leaking so long. I put it all back together. I retested and my fuel pressure did not change, HOWEVER my intake backfire is now gone. Why would this happen? Also when taking it all apart this spring came out and I am not sure where it came from. Anyone know? Car drives a lot better and seems to make better power. It is amazing how smooth these inline sixes are when they exhaust actually goes through the muffler and does not leak out at the manifold.

Name that spring!

[Ben's Z]

Also, my temp gauge is not working now. I put in a new sensor earlier this year and it worked before I started this project. Is there a ground for this sensor I could be missing?

[5thhorsemann]

Ben, I think you should start a new thread regarding the spring, it may have something to do with the temp sensor.

Obviously I'm talking out of my A$$ on this, I know almost nothing about the 280 EFI, but there are a bunch of members that know it inside and out.

[grantf]

Car drives a lot better and seems to make better power. It is amazing how smooth these inline sixes are when they exhaust actually goes through the muffler and does not leak out at the manifold.

[ATTACH=CONFIG]49940[/ATTACH] Name that spring!

I know what you mean, my engine sounded and ran TOTALLY different after I put a new gasket in.

May sound stupid but double check the conection?? I had the same promblem and it was a dirty contact at the temp sender.

Edited December 20, 2011 by grantf