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1985 Cadillac Seville Elegante
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222 Posts
Discussion Starter #1
I have had an 85 Seville now for about 4 months with no engine issues, the coolant seems to bob up and down oddly. Will lower then rise back to the prior level after cooling dont know why but no worry signs yet so ya. My question is for all you guys how many miles do you have on your engine?. I read an article joking these were known by mechanics to average 20k miles. I am currently at 91k plus. Share your info, thanks.
 

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'85 Fleetwood FWD
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728 Posts
Mine has around 110K, but camshaft replacement was one of the items I did. It sat around a few years before I bought it, so it's understandable that it likely got rust on it.
The 20K joke you mentioned sounds like a late 40s Lincoln V-12, which was a real sludge pump, and was not much on longevity.
 

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1985 Cadillac Seville Elegante
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222 Posts
Discussion Starter #3
Yea. Seems the 85+ models were worked out mainly. Though I am going to keep up on coolant flushes and oil changes to make a smooth run.
 

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'85 Fleetwood FWD
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728 Posts
There's been a bit of discussion here about the cooling system tablets additive. I've haven't used any yet. They seem to be like Barsleaks additive from what I read.
I use diesel oil in my engine, 10W30 or 10W40, because it still has the zinc and other anti-wear additives that were removed from most oil a few years ago to help with emmisions control. These older engines with flat-tappet cams need all the anti-wear stuff they can get:)
 

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1985 Cadillac Seville Elegante
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222 Posts
Discussion Starter #5
I'm about to do a oil change on my 4.1 unleaded running one. That diesel still safe oil to use?.
 

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'85 Fleetwood FWD
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728 Posts
That's all I use on older flat-tappet engines, but Royal Purple oil has some types with the additives also, like for marine engines. I use Chevron diesel oil usually. If you look on an oil container for CI-4, or CI-4 plus, that's supposed to be the additive we need.
 

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1926 Model T street rod, 2000 Jaguar XJ8, 1999 Corvette.
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The surging coolant level means there's air trapped in the system. Best way to purge the air is remove the radiator cap with engine cold. Put the climate system at 90 degrees to open the heater valve. Then start the engine. Have a friend hold the RPM up around 12 to 1500 RPM. After 5 or so min. the coolant level will drop quickly, at that time without lowering the RPM, top off the radiator. Then quickly replace the radiator cap with a new one. Once the cap is on, let the engine come back to a normal idle, lower the heat display to 70 and let it run a few min. watching the recovery tank to possibly top off as well. I say NEW cap because old caps weaken over time and wont hold proper pressure. The sealant pellets are VERY important to the life of this engine. Also new coolant every 24 months is just as important. Old antifreeze looses its anti corrosive additives after 2 years and will allow corrosion and eventual failure of the intake gaskets. That then leads to camshaft failure then main bearing failure, then engine replacement!
 

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1985 Cadillac Seville Elegante
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222 Posts
Discussion Starter #8
Yea I had a feeling about the air you speak of. I popped the good driving from west minneapolis to Hudson and smelled it from near the cap. Then after cool down it restored level. So eh. Thanks again, ill be sure to pick up some of those tablets. Seems to be this engines magic pill for life. Anyone have ideas on a replacement engine for this car?. Its a FWD seville 4.1 and though a northstar would be hilariously nice to have, I know this car cant,,,,, tear. Thanks again carnut.
 
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