Rear eng mount ring bolts frozen

MotorheadTed

Seaman
Joined
May 2, 2011
Messages
50
Have tried 1/2" breaker bar, impact wrench, no luck. Cut heads off ?? Or disconnect engine from bell at engine? Or ???? onlyy heat source I have is 750 deg F heat gun.
 

Glastron_V210

Petty Officer 1st Class
Joined
Jan 28, 2009
Messages
324
Re: Rear eng mount ring bolts frozen

I'd give them some mild heat with MAP gas (hotter than propane), then try again. You need to get some heat on these.

I've had trouble with these, and it's usually that the backside of the heads have corroded to the outer ring.

Ordinarily I'd say twist them until they break, but the nuts are captive in recesses in the flyweel cover (Cast AL). If the bolts are corroded into the nuts instead of the outer ring, you may break the cast AL recesses before you break the bolts, which is not a good idea.


If you can't get them, I've used a dremmel and cold chisel to get the heads off. It's kinda tight in there. Patience is required!



Once the heads are off and you remove the engine/flyweel cover the bolts can usually be turned out of the flywheel cover with your fingers.


Chay
 

billbayliner

Chief Petty Officer
Joined
Jun 30, 2006
Messages
553
Re: Rear eng mount ring bolts frozen

you say rear engine mount ring bolts. are you talking about the f/c clamping ring bolts?
if the heads are rusted away you may need to drill them off and sacrifice the clamping ring by drilling a series of holes across it and then split it open in several areas with a chisel. the new tap bolts will cost you more than a used ring.
5O15V15Q63k63mb3p4bb931b599223cd41f70.jpg


there are the six aluminum bosses where the threads are.
if you pull the engine from the f/c heat these up and expand them .
IMG_0451.jpg


no nuts on these that I know of unless Chay is talking about the borg warner pattern bolts for the adapter housing .
images
 

MotorheadTed

Seaman
Joined
May 2, 2011
Messages
50
Re: Rear eng mount ring bolts frozen

Thanks for the tips guys ! Main problem was the rusted heads which rounded off on some of the bolts. Used a 6 pt impact socket with a 1/2 " brkr bar with 18" extension on the bar, and broke 3 loose. Once they broke loose you could turn them out with your fingers !!! On the 3 rounded heads I forced a 6 pt metric socket ( 12 or 13 mm ) which was a bit smaller and broke the remaining 3 loose, they were really torqued in tight !!
Ted
 

billbayliner

Chief Petty Officer
Joined
Jun 30, 2006
Messages
553
Re: Rear eng mount ring bolts frozen

Ted its no so much that they were torqued in tight,, its that corrosion kept them from coming loose easily. good call on the six point and metric socket. been there and done that.
btw, these are 3/8" nc galvanized tap bolts. you can order them from a bolt supplier and save some money.
use thread sealant or marine antizeez on the threads and they ll come loose next time
 

MotorheadTed

Seaman
Joined
May 2, 2011
Messages
50
Re: Rear eng mount ring bolts frozen

Bill:
Thanks for the info. I'm familiar with "self-tapping" screws, but I've never heard of "tap bolts" !
Are you saying that these bolts tap their own threads into the housing? and since the threads ARE NOW in the housing, why would you not use regular bolts ? I was planning on using stainless, as I did for 20 yrs with every bolt I could on my Bert 28, with no problems whatsoever.
 

billbayliner

Chief Petty Officer
Joined
Jun 30, 2006
Messages
553
Re: Rear eng mount ring bolts frozen

No,,, a tap bolt is threaded its entire shank length. youll be buying a good grade galvanized bolt and the threads will be roll formed (not cut threads) .


BTA%20TAP%20BOLT%20GR.2%20ZINC%20FULL%20THREAD.jpg
 
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