Radiator Boils Over, But Engine Is Not Hot

October 17, 2009/Steve Tackett

MOTOR MATTERS ASK THE AUTO DOCTOR BY JUNIOR DAMATO

Dear Doctor: The radiator in my 1991 Honda Prelude gets hot and boils the antifreeze mixture. I let the engine run with the radiator cap off. I can see good fluid flow in the top radiator tank. Some bubbles form, intermittently at first, then the fluid level rises and overflows, followed by a rather violent eruption at about the same time the cooling fan comes on. Is there some way for the radiator to be getting this hot without the engine getting that hot? Warren
Dear Warren: Take the car to a shop that has a gas analyzer. A check of the cooling system for hydrocarbons will need to be performed. Leaking cylinder head gaskets are a common fault in this engine. If the hydrocarbon test is negative, then the next step is to check the water pump impeller.
Dear Doctor: I own a 2003 Saturn Ion. In cold weather the car doesn’t start up when I first turn it over. I have to let it sit for 10 minutes and then it starts and runs fine. People tell me the problem is with the ignition coil. Do you agree? Ed
Dear Ed: Take the car to a shop and let it sit overnight. The next morning the technician will connect a scan tool before starting the engine and read all the input sensor values. A weak coil is always a possibility, however, before replacing parts we always check sensor values before attempting repairs.
Dear Doctor: I own a 1996 Lincoln Continental with 98,000 miles. The air suspension is acting up and the suspension air compressor is loud and seems to always be running. I understand to replace the suspension and compressor it is very expensive. Are there any alternatives to the expensive replacement of the suspension airbag system? Jude
Dear Jude: At my shop whenever we see failing air suspension systems on Ford and Lincoln vehicles we change the air suspension over to trouble free conventional coil spring suspension. Any good repair shop should be able to make the change over.
Dear Doctor: Our son owns a 2004 Chevy Silverado. The odometer set itself back to zero miles — and remains at zero miles. Click edit button to change this text. Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut elit tellus, luctus nec ullamcorper mattis, pulvinar dapibus leo.

1991 Honda Prelude

The dealer wanted proof of the mileage from the last oil change receipt, but it turns out the vehicle was not under warranty. I researched and learned the dash cluster is a big problem with the GM trucks. Should this have been a recall? Rena
Dear Rena: A lot of these trucks were recalled — including my own 2004 Silverado. You did not mention if your son is the original owner of the vehicle or whether he may have received a recall notice from GM. However, we do service a lot of these problems and the cost of repair averages $300. This includes removal of the dash cluster, repair and reinstalling the cluster.
Dear Doctor: I recently purchased a 1953 Ford Custom Line with a Flat Head V-8. I would like to switch to full-synthetic oil. What is your opinion with synthetic oil on this older vehicle? Mike
Dear Mike: Today’s engine oils are designed to the late model vehicles we now drive. The internal engine parts — especially the camshaft and valve lifters — are very different than the early days and require a different oil blend. With an older engine, such as your 1953 V-8, zinc additive is a must and it is not found in either synthetic or regular petroleum based engine oil. There are oils designed for older engines available at performance stores.
Dear Doctor: I own a 2008 GMC Canyon with the 4-cylinder engine. I changed the oil at 1,200 miles with full-synthetic oil and reset the oil change indicator. At 5,200 miles I changed the oil again but I did not reset the computer. The oil change light finally came on at 8,600 miles. I now plan to use synthetic oil and change the oil every 4,000 miles. What do you think? Jeff
Dear Jeff: Oil reminders are based on time and mileage and not actual oil condition as many owners think. There are no meters in the system to actually check oil condition. The truck will be fine with your schedule.
Dear Doctor: My friend just purchased a brand new 2010 Subaru Outback. The engine has a chirping sound while idling or driving at 900 to 1,400 rpm. The Subaru dealer can hear the sound and thinks it is a problem. He replaced the water pump, but that did not resolve the noise. They have contacted Subaru. Have you heard of this problem and how to solve it? Steven
Dear Steven: This is a brand new model and it is too early for me to access problem information. I recommend you continue to work with your dealer on this issue.

Junior Damato is an ASE-certified Master Technician.

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Copyright, Motor Matters, 2009