: '99 DeVille, probably blown head gasket

10-11-10, 05:59 PM
Hey folks!
I just picked up a 1999 Devile Concourse with the L37 engine. All indications are that it has a blown head gasket. And I am preparing to pull the engine and have the heads gone over. This is the first Cadillac that I have ever driven, and I can say with fair certainty that it will not be my last. What a nice car.

Anyways, I have been looking for and haven't been able to find any information on gains from porting and polishing these heads. (Before you all start Poo-pooing a newb coming in here and saying that, I am the son of an auto-machinist and married the daughter of a skilled mechanic, so the tech stuff is covered. ;)

I am also wanting ot get recommendations about replacing the water and fuel pumps, and anything else that might need it while the engine is out of the car.

Thanks all.

10-11-10, 07:02 PM
there's lots of info here about the HG problems that N* cadillacs have... the main one being the head bolts pulling out of the block

someone else will probably chime in with a bit more info and maybe some links for further reading, but first up in the black at the top of the page read the Technical Archive
also check out the sticky's here http://www.cadillacforums.com/forums/northstar-performance-technical-discussion/

and :welcome5: to the party

10-11-10, 11:22 PM
The factory service manual is really helpful. You can get them on ebay.

There are several (many) threads on doing HG's. You can drop the cradle or pull it out the top. The cradle drop is my preference.

The gains from porting would be minimal but if you have the equipment it might be worth it. When you get the heads off you'll see that they are well cast and clean. Some of the things I've been reading indicate a performance valve job may get more power than porting on newer style heads because the ports are so much better than old designs.

10-12-10, 10:45 AM
:welcome: Welcome Aboard !!!

GM already did your head work for you. There is precious little concerning work on these pent-roof heads because they're already tricked out from the factory.

Remember that you're working with a PCM-controlled powertrain and there are NO tuners or chips for it. (1997 back, yes - later, no.)

Read as much of Northstar Performance and the Cadillac Technical Tips as you can stomach. You have a very steep learning curve in a 99 Concours. Especially when it comes to using Timeserts, Norm's Inserts, or Jakes studs (recommended) for the block bolt hole thread repair (the cause of the failed head gaskets).

99 was the last year for flat tappet cam followers, so do a thorough head check - those followers tend to dish with the new oils which have less of an anti-scuff package. Consider running Shell ROTELLA 10W-30 fleet oil.

Can't hurt to replace the water pump - special socket, comes out with a 1/5 turn clockwise, line up the retainer tangs properly (small tang at 1:00) - goes in with a 1/5 turn counterclockwise torqued to 73 ft/lb.

Read the ENTIRE Cadillac Technical Archive up ^^^ in the black bar.

Get a real GM/Helm Service Manual or subscribe the car to www.alldatadiy.com