1992 Cadillac Eldorado Engine Knock

1992 CADILLAC ELDORADO
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BLUEYEDCAPTAIN
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Can anyone help please? I have a 1992 Cadillac Eldorado Touring Coupe with 4.9L engine with 233,000 miles on it. It has JUST started to KNOCK TERRIBLY EVERYTIME I start the engine. After about 5 minutes of running, the knock goes away. The engine DOES NOT overheat. My thoughts are that I am getting water mixed in the oil since I loose water quickly. Here is what my radiator cap looks like:[img:8c77115402]http://www.2carpros.com/forum/automotive_pictures/56243_KIF_1014_2.jpg[/img:8c77115402]
Here is what my oil cap looks like? I see some white on the cap, but when I look inside the engine or pull the oil dip stick, it all seems fine...[img:8c77115402]http://www.2carpros.com/forum/automotive_pictures/56243_KIF_1015_1.jpg[/img:8c77115402]
Here is the engine:[img:8c77115402]http://www.2carpros.com/forum/automotive_pictures/56243_KIF_1016_1.jpg[/img:8c77115402]
I have been told things like a head gasket, leak in a manifold, pull spark plugs to look for water, exhaust leak??? Can anyone please give me more information?? THANKS MUCH!! Marty
Jan 30, 2007 at 2:57 PM
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MERLIN2021
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The radiator, if the tranny cooler lines attach to it, can leak tranny fluid into the radiator! Check your transmission fluid! If you have a small bit of white oil on the cap, change pcv! As for the knock, connecting rod or wrist pin!
Aug 13, 2007 at 9:13 AM
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BUZZSAW
  • ✓Experienced Mechanic
  • 1,198 POSTS
[quote:ec3f68bdf6="merlin2021"]The radiator, if the tranny cooler lines attach to it, can leak tranny fluid into the radiator! Check your transmission fluid! If you have a small bit of white oil on the cap, change pcv! As for the knock, connecting rod or wrist pin![/quote:ec3f68bdf6]

man oh man, if coolant is getting into the oil, the intake manifold gasket is leaking, remove the valve covers and pressure test the cooling sys to check this and if you have a knock from it replace the engine dont let someone replace the gasket it will cost you more in the long run
Sep 17, 2007 at 8:46 AM

Suggested Repair

Check the transmission fluid in case the radiator cooler is cross-contaminating fluids, and replace the PCV valve if the oil cap shows milky residue. Remove the valve covers and pressure-test the cooling system for an intake manifold gasket leak. A cold knock that fades may be a connecting rod or wrist pin; if coolant in the oil caused the knock, engine replacement was advised rather than only replacing the gasket.

Conversation Summary

A 1992 Cadillac Eldorado with a 4.9L engine and high mileage developed a severe knock at startup that disappeared after about five minutes, with no overheating but rapid coolant loss and some white residue on the oil cap. Experts suggested checking the transmission fluid, replacing the PCV valve, and pressure-testing the cooling system for an intake manifold gasket leak. They also noted a possible connecting-rod or wrist-pin knock and advised engine replacement if coolant contamination caused the knock.

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