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Original Engine


Cadillac Jim

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This is the 300 HP Northstar, original mid-year 1997 production. I always felt free to nail it, and it never burnt oil until I got some bad oil at about 75,000 miles. After that it burnt a quart every 1,200 miles. I never tried Bruce's WOT treatment, but I should have, just to see what it would do. From my experience with much older engines, I have an inhibition about engine braking at high RPM and that part is key to Bruce's technique, because it both exercises the stuck rings and pulls oil up through them and helps clear them. But, I never did that with my engine.

It's very clean inside, which is not unexpected because I always changed the oil at 3,000 mile intervals and almost always use synthetic oil. The EGR passages were clear. I red-line it a lot, and I was interested in the cam chain tensioners and guides, but they show no signs of wear at 116,600 miles of my lead foot. So, we can all tromp away and let it wind through the sweet spot with impunity. I do tend to blip off the throttle at the shifts in order to be polite to my transmission, unless I'm pulling it down lower than Drive to get firm shifts, which is rare.

The reason that I'm changing the engine is an overheating problem. It began in January with a sudden temperature spike a minute or two after a speed burst. It asked for coolant the next time I started it. This got gradually worse, and lately it overheats every time I top a hill and come off the throttle, about every 10 miles. A pressure test verified cylinder leakage into the coolant, and with the mileage and other maintenance issues I decided on a remanufactured engine. It's out of the car today, with the new one completing installation, and I took a picture of a coolant leak from the left head. It was under the master cylinder where it couldn't be easily seen until the engine was out. Click on it to see it full size. Note the crack in the head gasket sealer and the residue from coolant running off the edge to the right on the flat spont on the block.

[attachmentid=2627]

Smoking gun.

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CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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  • 2 weeks later...

Due to my experience in my Northstar, I decided to look at my wife's 1999 Pontiac Grand Am with 3.4 liter V6. It has aluminum heads and has never had the coolant changed. It's very low mileage and nobody has suggested changing the coolant. However, it needs coolant every couple of months. I had it pressure-tested, and indeed there is water seepage at the water pump and at the intak manifold gaskets due to coolant corrosion.

Change your coolant every three or four years. Better safe than sorry. It's not too late for my wife's car, but it would have been better and cheaper to change the coolant three years ago.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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  • 8 months later...

Due to my experience in my Northstar, I decided to look at my wife's 1999 Pontiac Grand Am with 3.4 liter V6. It has aluminum heads and has never had the coolant changed. It's very low mileage and nobody has suggested changing the coolant. However, it needs coolant every couple of months. I had it pressure-tested, and indeed there is water seepage at the water pump and at the intak manifold gaskets due to coolant corrosion.

Change your coolant every three or four years. Better safe than sorry. It's not too late for my wife's car, but it would have been better and cheaper to change the coolant three years ago.

The GM 3100 AND 3400 engines are known for having upper intake manifold gasket problems. I replaced them on a friends 3100 (do a search here, I posted the job here) and I am about to do my wife's Monte Carlo with the 3400 engine. I would not be surprised if yours are leaking. The intake manifold gaskets have been redesigned. My wifes intake gaskets failed at 3 years and about 40,000 miles, therefore not related to coolant changes, Mike

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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  • 1 month later...

Mike -- my wife's Pontiac had been using about a quart of coolant every six months for a few years. I asked her if the dealer had ever recommended a flush and she said that she didn't recall, so I had it pressure tested. Our mechanic said that a lot of those particular V6's had manifold leaks -- just what you say. Our mechanic also said that these leaks, left unattended for too long, could eventually get coolant in the oil and bring down the engine. I assumed that it was due to old coolant, but in any case we should be good to go now. Her car is very low mileage and she doesn't drive it much, so, with proper care, it could last into the mists of time, and that's our plan.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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