Reply With Quoteit's talking about pulling a 35 degree angle on it, like 90 degrees is a 1/4 of a turn and 45 degrees is a 1/8th of a turn
final head bolt torque question
I am at the last stage of the torquing for my 1990 535i (Just got a new head gasket and head).I am baffled as to the third stage. I purchased a protractor and am ready to finish the car... but after talking to my mechanic friend, am not sure I am reading the Bentlely manual correctly. It says that after stage two of the torque (to 58 ft pds) I am to let the car run for 20 or so minutes and then do the final stage. My question is, for the third stage, the Bentely says: "35 + 5 degrees" Does that mean I am to torque the head bolts to an additional 35 ft pds.over the 58ft. pds? or does that simply mean that the protractor is all I use on the final stage and only turn the head bolt a mere 35 degrees? My friend has me wondering since he never heard of such a low torque setting for the head bolts. Can anyone offer me final advice on this?
5-10 Grand Master
it's talking about pulling a 35 degree angle on it, like 90 degrees is a 1/4 of a turn and 45 degrees is a 1/8th of a turn
all america wants is cold beer warm cat and a place to take a poop with a door on it
Super Moderator
Its like Winfred said, the final torque is 35 degrees period over and above the
second stage torque which works out to a fairly high number, the bentley's isn't allways correct. The actual bmw specs as shown just state 35 degrees they don't give an allowance of plus or minus 5 degrees like the bentley's does. Your mechanic friend is probably used to irons head and iron blocks, when you bolt an aluminum head onto an iron the with steel bolts the aluminum expands alot more than the iron head does when its heated up so the torque greatly increased on the aluminum head when its warmed up since the bolts and block dont expand as much. Iron heads and steel bolts expand at about the same rate when heated so they require more torque when cold since it stays about the same when heated up. Thats also the reason that head gaskets fail more often on iron block , aluminum head motors and on all aluminum motors...
Originally Posted by tjn
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