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Posted: Friday, September 19, 2014 10:31 PM

This info is for anyone that wants to know about how cooling system works how to diagnose them and recommendations on what to do when confronted with an overheating problem.

When you have an overheating problem you could think, What was first, the chicken or the egg? That question has been nagging consumers and technicians alike for years. Thank god there are some people that investigate and go to school to obtain the knowledge necessary to solve these crazy problems.

Here you have some Help to diagnose an overheating engine.

My car is overheating, what should I do? Can you replace my head gasket?

I hear this question a lot in my profession. And people usually don’t like my answer. You see, I don’t really want to do a head job on their car. Why? Because to do a head job properly first of all the car has to be diagnosed properly. The diagnostics procedure is not easy and parts have to be removed from the engine meaning it is not cheap to diagnose. And to do a head job properly the customer needs to spend a considerable amount of money

I opted to offer my customers to instead replace the engine most times. Because normally when an engine is overheated it self destructs. People have a hard time accepting this. They tell me that the engine still runs and that it was just a leak. That the engine must be good because it still runs. Sorry but hidden damage is the one thing they need to worry about if oil and water mixed. The result of this, bearings damage. And it can only be detected by disassembling the engine or starting the engine to listen for knocking sounds etc. Some times rods get bent because water entered the combustion chamber. There are other areas where there could be heat related damage. One example is the pistons, rings and cylinders. They are very sensible and can easily get damaged due to excess heat.
Many times the vehicle comes with a no start condition so some techs go ahead and do a head job because the saw milkshake (Oil and water mixed) and then they get a nasty surprise…knocking sound coming from rod bearings. Not nice at all I know. The customer has wasted money and the technician may not be looking too professional in the end.

Whe you do decide to perform a head job.

Here are the parts needed to do a complete and professional job.

• Head gasket set
• Machine and test heads or replace damaged ones.
• Use new bolts.
• Use new hydraulic lifters.
• New thermostat.
• New hoses.
• New belts.
• New water pump
• New radiator and cap.
• Perform a tune up.
• Replace oil and filter.
• If coolant was present on the exhaust you will need to replace the catalyst/s and oxygen sensors.
• If the car has a timing belt there are other parts that have to be replaced.
• Radiator fan/s and relay if not operative.

If these parts are not replaced when the job is done then you are doing an incomplete job and the engine is at risk of giving the customer more trouble down the road. Remember, when you fix a car people are more likely to blame the tech for anything that happens soon after (you are married to that car). Or even later on. So you need to make sure the repair is done properly and it will last.
But as we all know most people will opt to take the car to a cheap mechanic that will patch up the job to “save” some money to the customer and then things usually get ugly. Not a nice thing.

A head job can be done successfully if the car is a low mile car and meets certain criteria. If the tech determines that all the components are ok and the head gasket is leaking (Meaning the car overheats slightly and only sometimes) then you can advice the customer to do a head job. But still, remember the customer will hold you accountable for any post problem if you don’t inform him of the risks of not replacing all the recommended parts.

As you can see doing a head job is something complicated. It should be done only by a professional following these guidelines. If you do shortcuts you will surely have to face the consequences. Fact.
This is why I recommend a good, low mile used engine as an alternative of doing a head job. Of course a good engine swap also benefits from refreshing the used unit. Something that will save you money in the long run. But of course this means more money.

Please read this.
Advice to the Customer By Steve Litt
Don't try to get off cheap in cooling system repairs. Overheats cause major consequential damage, such as broken head gaskets and even broken heads. Broken head gaskets in turn can cause broken starters and flywheels. Replacing a flywheel on a transverse engine is *very* expensive.
First ascertain the condition of the head gasket. If you're driving a cheap car, you may wish to junk it or sell it cheap upon hearing of a head gasket problem, especially if accompanied by a bad radiator. However, remember that all cars need repairs, and the car you replace it with might also need expensive repairs. So if it's a good, reliable car in reasonable condition, it's often best to bite the bullet and do the repair, even to the tune of $2000.00.
Once you've committed to making the repair, replace *all* bad and semi-bad components. If the water pump leaks or has excessive play in the bearings, replace it even if it might not have been the primary root cause. If the radiator is partially clogged, replace it. You don't want that radiator clog to rear its ugly head on a 3000 foot climb.
I consider a finding of clogged radiator to be an opportunity to get a heavy duty radiator. I spare no expense on radiators. A high capacity radiator can compensate for a host of other problems. When my Dodge Coronet radiator needed replacement, I had Harry at Valley Radiator build me a 17x25 4 row monster. It cost me $400.00, but let me tell you, when I drove it across the country in one of the worst heat waves ever, I was darned glad I spent the money. If you don't have a radiator shop you trust enough to custom build you a thyroidal radiator, or if you have a recent car that can't take a custom radiator, ask for the stock radiator that comes with the car's "towing package". Such a radiator is designed to dissipate the heat generated while towing a trailer up a 3000 foot climb. The extra $100 or so will be greatly appreciated as the years go on.
Sometimes you have the option of repairing the radiator. If you already have a heavy duty radiator, and there's a real opportunity to restore it to like-new condition, maybe you'll choose to repair the radiator. But you would still have deposits and diminished capacity after repairing the radiator, I'd personally choose to buy a new radiator instead of attempting the repair. A top functioning radiator is your best defense against long steep climbs or long drives in hundred degree weather.

For more info on this subject please go here and read these excellent articles by Steve Litt. Although he admits that he is not a technician he wrote some excellent info there to illustrate how the cooling system works. One thing he is wrong about is the mention about removing the thermostat. Yes you can remove it to test, but many times the car will run cooler not because the thermostat was bad but because there was partial restriction on the radiator or somewhere else. It seems many old school mechanics think they know more than the engineers that designed the engine and many opt to just leave it removed. But the real problem was the radiator by being partially restricted will make the car overheat some. Removing the thermostat helped the pump overcome the restriction by allowing more water to go by it. The thermostat has a regulated opening. The size of the hole determines the amount of water that goes by. Plus it regulates when the water starts flowing.

By Pedro Talavera and Steve Litt.

Owner of CMT of Miami. Mobile Car Repair.


Contact: (786) 344-9571

• Location: Miami, CMT of Miami

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