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Port coil bracket mounting bolt threaded hole missing, well kinda'
Hello Afourians,
Here is the rest of the coil bolt conundrum....I hope this doesn't turn out to be a critical error for my A4 due to my curiosity.
I am remounting from a known good running A4, a new (used) coil with a used ballast resistor. Looking at my spare engine from which I removed the coil, coil bracket and resistor ( tested to .9 ohms), I saw there should be two (2) coil bracket bolts, my engine in my boat only had one on the stbd. side of the coil bracket. hmm whats going on here???
Digging around I uncovered a painted bump where I expected to find the second threaded hole for the port bracket bolt under the existing coil bracket. It was a painted over bump slightly protruding from the case.
So I picked around with a dental pick and a punch and a magnification hood at 1 AM. My marina mates now really think I have gone mad.
Paint and a small chunk of what looks like some kind of epoxy filler came out.
Looking closely after cleaning it up I saw what appeared to be a stub of a bolt with something inside that was of different metal than the bolt stub...now what???
I tapped around and tried to grab the inside piece of metal, it did stick out enough to entice me to try to grab it. The whole thing definitely looked like a drilled bolt stub with something of different metal stuck inside. I could not budge it.
Next day... I have access to liquid nitrogen. Nitrogen is great for sorting out metals with different expansion rates...so I tried a shot nitrogen after trying every way to get the interior fragment out. I was able to pull it out by twisting and pulling while cold, it took a few attempts and some choice words.
It was a tough piece of metal. Out comes a fragment of a bolt extracter. GAADS! but it was intact so I think I got it all.
I probed around inside and flushed out with PB BLaster. Realized I had a pre-drilled bolt stub. How nice, predrilled!
BUT IT GETS BETTER. I could stick the PB BLaster red tube all the way into the case through the "pre-drilled" hole and it came out with a sample ot the interior, a sooty residue. Tried it many times so I know it is true. I can see that the hole where the little red PB tube goes into the engine is just near the center of the hole, it is not the entire diameter of the hole that was drilled into the bolt, It looks like just the tip of the bit that was used to drill just penetrated the case.
Where am I? In the chamber with exhaust gasses or worse in the cylinder?? It is near #4 cyl.
Is this engine NFG? or do I slap some more filler on it or try to use an extracter and easy out the bolt? After all it is ready and waiting. I have the extractor fragment and will get it sized at the parts store.
Your help with this A4 addiction will be greatly appreciated.
Sincerely,
Elizabeth
of Bristol 29 fame
Here is the rest of the coil bolt conundrum....I hope this doesn't turn out to be a critical error for my A4 due to my curiosity.
I am remounting from a known good running A4, a new (used) coil with a used ballast resistor. Looking at my spare engine from which I removed the coil, coil bracket and resistor ( tested to .9 ohms), I saw there should be two (2) coil bracket bolts, my engine in my boat only had one on the stbd. side of the coil bracket. hmm whats going on here???
Digging around I uncovered a painted bump where I expected to find the second threaded hole for the port bracket bolt under the existing coil bracket. It was a painted over bump slightly protruding from the case.
So I picked around with a dental pick and a punch and a magnification hood at 1 AM. My marina mates now really think I have gone mad.
Paint and a small chunk of what looks like some kind of epoxy filler came out.
Looking closely after cleaning it up I saw what appeared to be a stub of a bolt with something inside that was of different metal than the bolt stub...now what???
I tapped around and tried to grab the inside piece of metal, it did stick out enough to entice me to try to grab it. The whole thing definitely looked like a drilled bolt stub with something of different metal stuck inside. I could not budge it.
Next day... I have access to liquid nitrogen. Nitrogen is great for sorting out metals with different expansion rates...so I tried a shot nitrogen after trying every way to get the interior fragment out. I was able to pull it out by twisting and pulling while cold, it took a few attempts and some choice words.
It was a tough piece of metal. Out comes a fragment of a bolt extracter. GAADS! but it was intact so I think I got it all.
I probed around inside and flushed out with PB BLaster. Realized I had a pre-drilled bolt stub. How nice, predrilled!
BUT IT GETS BETTER. I could stick the PB BLaster red tube all the way into the case through the "pre-drilled" hole and it came out with a sample ot the interior, a sooty residue. Tried it many times so I know it is true. I can see that the hole where the little red PB tube goes into the engine is just near the center of the hole, it is not the entire diameter of the hole that was drilled into the bolt, It looks like just the tip of the bit that was used to drill just penetrated the case.
Where am I? In the chamber with exhaust gasses or worse in the cylinder?? It is near #4 cyl.
Is this engine NFG? or do I slap some more filler on it or try to use an extracter and easy out the bolt? After all it is ready and waiting. I have the extractor fragment and will get it sized at the parts store.
Your help with this A4 addiction will be greatly appreciated.
Sincerely,
Elizabeth
of Bristol 29 fame
. No harm is done; just retap the hole with 5/16" NC and put in a short cap screw as a "plug" (use lots of #2 Permatex goo). BTW, it's best to relocate the coil off the engine so it can run cooler.
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