Sorry if !! offended .... just trying to save people from making a mistake.
I agree Fred had influence. But I find it significant that this method is not in the 1986, 1989 official shop manuals or in the very nice engine overhaul manual (I think Black wrote).
What actually happens when you squeeze the hose …. early cars with no expansion tank where fluid level was generally below the cap level --- with a good cap it might create 7 psi vacuum .... is that really enough to pull all the antifreeze in the head toward the radiator instead of up the head bolt it surrounds when the vacuum is broken by loosing the head bolt nut? From trying this idea (probably about 1975 on my Duetto), it didn't.
For early expansion tank cars (like 1975 bulletin), squeezing the hose pushes fluid back into expansion tank temporarily .. I say temporarily because the expansion tank cap is not a "seal" but more of a "splash guard'. Since the expansion tank is not sealed, where is the vacuum?
Technical Service Bulletins (TSB) are a separate standalone means for a factory to communicate updates, procedures, product changes, etc. with it's service network. In Alfas case, very few, if any, TSBs make it to the next issuance of a workshop manual simply because a new or updated version manual may never be published. Revision 'packets' may be issued from time to time as single page inserts into a loose-leaf manual but these updates are generally for newer model specs and data. And, and course, issuing single page updates for hardbound manuals is pointless. So Alfa leaves TSBs for TSB only manuals.
As far as the procedure goes, one does not need to create enough vacuum to reduce the coolant level to below the deck level. This would be impossible anyway since the quantity of coolant in the system remains the same. The idea here is to create just enough negative pressure in the cooling system so as to prevent the coolant from RISING up and out from around the stud, not to actually lower the level. And only a few mmHg is needed.
There a number of reasons I can think of why this did not work for you.
1) insufficient coolant
2) faulty radiator cap
3) leak in radiator top tank
4) hose not squeezed enough
5) hose had insufficient memory
Whether or not the car has an expansion tank is irrelevant; the negative pressure formed is in the cooling system, not the expansion tank.
Concerns of coolant getting on the gasket when a head nut is loosened are unfounded simply because if a 112mm thick chunk of aluminum flexes enough between two fixed points only what, 18cm apart, then the head is already broken. Besides, special tools have been created specifically designed to break the head gasket seal even after ALL 10 head nuts have been removed.
You just gave 5 potential failure points to the method, why take the chance?
I believe you were a factory trained mechanic, did you use that method at the dealership?
Sort of on topic …..yesterday was I talking a factory trained mechanic that 40 years later is still building Alfa engines ….. since this topic had popped up I asked him for opinion on periodically re-torqueing heads ….. "is there oil in the radiator …. no …… then let sleeping dogs lie". Would like to hear your opinion on that also.
If the head/block interface is ~6" below the top fill of the coolant, that would be 6" H20 pressure at the interface, which is only about 0.2 PSI. So you'd only need the hose trick to generate that much vacuum for it to work, which seems pretty reasonable.
For comparison, apparently by sucking on something a human can generate ~5 PSI vacuum.
Has the vacuum trick ever not worked for me? Yep. Quite a number times actually. But had I not attempted it, 4 of the 5 what you termed 'failure modes' may have gone undetected. Topping the list were low coolant levels followed by bad radiator caps and then spent hoses. IOW, the vacuum trick is also a tool that can be used to find other faults.
Will I retorque the heads of my own cars? Sure! Main reason is I like to tinker. After a few retorques though the head gasket is no longer compressible so there's no need to.
Please ask your factory trained mechanic if, when an L4 engined car comes in that leaks a bit of coolant between the head and block on cold start up if he'll replace the head gasket or do a retorque.
Oh, not factory trained nor ever worked in a dealership.
I really do think this thread is dangerous and putting out an incorrect concept, ie. That retorquing a cylinder head is some sort of maintenance task. It isn't but yes has to be done when a head gasket has been replaced.
I can see some poor new to old Alfas buying a lovely original 105 that is running perfectly CAUSING a head gasket failure by fiddling and doing an unnecessary retorque. Then another person is spreading the incorrect myth that these engines blow head gasket faster than a *****s draws hit the ground ...
Agreed. In fact that is posted earlier in this same thread:
"This question of this thread isn't "do you think re-torquing is a good idea". The question of the thread is "is this a good procedure if you are doing a re-torque"."
It is up to the user to decide if a re-torque fits their circumstance. If they do, this thread simply attempts to collect best practices from across a variety of BB head re-torque threads and put them all put in one place.
Good summary, Crackie!!
Just to throw my 2cents in, with a comment on "Sort of on topic …..yesterday was I talking a factory trained mechanic that 40 years later is still building Alfa engines ….. since this topic had popped up I asked him for opinion on periodically re-torqueing heads ….. "is there oil in the radiator …. no …… then let sleeping dogs lie". Would like to hear your opinion on that also."""
I'd think, by the time one sees oil in the coolant, it's too late for a retorque...one is in for a rebuild or a new head gasket (at best)!! I'd think a compression reading would be a diagnostic step say every X years, if a defective reading is found then a retorque is an easy first step (admittedly many other causes can be at play here!!).
I've got a motorhome with a big Cummings Desiel in her and do a "Blackstone" engine oil analysis every other oil change...think I'll start doing this on my Spider just to see....microscopically coolant in the oil, OK try a retorque..visual oil in coolant...possibly too late!!!
I'm in a bit of a spot.... my gearbox is going back into my early '66 Duetto and my guy who is working on it just noticed the seal in the bell housing may look a little suspect.It seems soft and pliable, but I think he would feel better replacing it.
I believe C/L says it is a 605.16722...
Searches have this procedure all over the lot. This is NOT a BOSCH system. I have a SPICA system with a three hole starter and no lift. I'm looking to change out my starter and before I remove the air filter housing... I know about the shoulders bolts etc. My vision is to remove the air filter...
Please see the 2 images. I think I'm missing a part according to the diagram. It looks like a nut. Is it a special part or could I use a nut to fit the tensioner bolt from the hardware store? A picture of the part would be helpful.
I noticed that the 164 & 168 guys have a very active thread about what they've been up to, and I think us Spider guys and gals need to get with the program- so I'm gonna start and see what happens!
Today was a very good day! It was a beautiful warm, clear day in South Florida, and I'm sorry to...