Has anyone used Loctite 573 instead of 574 for sealing an engine case?
 

I have read the Ultimate Engine Sealant thread and am weighing the various options.

One frequent concern that pops up is the working time of 574. Evidently the clock starts as soon as you apply it, leaving precious little extra time to position the left case half, install and torque the through-bolts and tighten the case perimeter studs. One Pelican even went to the difficulty of rehearsing a three-man installation like a football play, and labeling in advance all the through bolts with the proper tightening sequence (good idea).

Now, I think I read somewhere that the factory originally used 573 but that most professional mechanics use 574 because it's faster to cure. Isn't that the opposite of what you want? Are 573 and 574 the same, just different cure times?

Many thanks in advance for any advice on the subject. I'm just about ready to order my glues and sealants.

here are the data sheets for both 573 and 574

http://tds.loctite.com/tds5/docs/573-EN.PDF
http://tds.loctite.com/tds5/docs/574-EN.PDF

Chuck

Thanks Chuck, you must be reading my mind as I was just reviewing those sheets. The products are VERY similar with a few exceptions:

-Lap Shear Strength: 190 psi (573) vs 1,230 PSI (574)

- % of initial strength when aged at 150C falls to 50% at about 1500 hours (573) vs. greater than 75% after about 250 hours (574)

-573 has a better resistance to gasoline after 100 hours than 574. Motor oil resistance is the same. I wonder if this makes a difference to cars that experience oil dilution e.g. MFI.

In any event, the technical properties aside, my question remains as to whether there is operational experience with 573 in addition 574. Experts?

The issue with 573 as a case sealant is really the shear strength, as you've noted. The 574 keeps the case much more tightly locked together, especially in critical areas like the through bolt main saddles. A bit of 573 is better than 574 on gaskets such as chain box, etc., as it allows the gasket to "find its home" and provides a more flexible (lower shear) seal.