Diagnosing Engine after overheating

[03protege]

Diagnosing Engine after overheating (please move to free parking)

I have an opportunity to buy my brother in-laws car that overheated for next to nothing (seriously he said he would sell it for a dollar), but before I go that route I would like to check and make sure the engine is solid.

What I know is the water pump seized (snapping the belt) and also one of the lines to the heater core (or the heater core itself) blew causing a leak on the interior.

I started the car for about 5-10 seconds and it sounds good, I can't hear/feel any knocking, no hesitation.

Basically I want to do some comprehensive tests prior to sinking any money into parts.



Will a compression test indicate a bad head gasket? Or would I need to do a cylinder leakdown test?

Eventually I will need to do cooling system pressure test but currently with the heater core leak and the leaky water pump I imagine this test won't tell me much. True or false?

When my Protégé overheated (and blew it's head gasket) it also spun a bearing any good tests to check for this? I couldn't hear any knocking and I do plan on dropping the oil pan to look for metal shavings.

Anything I miss?

Car is a 2007 Mazda 6s (v6) w/ 150k miles and is pretty well optioned. Trade in is around $4000-4500. So I would be comfortable putting around $1k into it.

Thanks in advance for the help you guys rock

 

[03protege]

Just realized this is not free parking!! Sorry mod can you move me?

Haven't had my go juice yet!

 

[theoldwizard1]

Basically I want to do some comprehensive tests prior to sinking any money into parts.

Will a compression test indicate a bad head gasket? Or would I need to do a cylinder leakdown test?

Leakdown for sure !

When my Protégé overheated (and blew it's head gasket) it also spun a bearing any good tests to check for this?

No. I had a friend who work at a Ford dealer in 90s and did lots of head gaskets on 3.8L V6 engines. He said about 50% spun the bearings withing 1-2 years after.

 

[redyute]

Cant go wrong for $1.00 just put a new pump on and belt load up the rad with some water loop the heater core lines to bypass the heater core then start her up and let her idle monitoring the tem gauge to see if she overheats. If she does not ever heat then drain the water for antifreeze and see what's going on with the interior leak. Its gonna be a ***** if it does need a heater core, talk about pulling the dash ouch lol

 

[03protege]

Leakdown for sure !



No. I had a friend who work at a Ford dealer in 90s and did lots of head gaskets on 3.8L V6 engines. He said about 50% spun the bearings withing 1-2 years after.

Thanks for the input.


What exactly causes the spun bearing? Is it the excessive heat or does it have something to do with coolant hydro-locking the cylinder?

EDIT: From some research it appears to be related to the coolant getting into the oil and then not lubricating the bearings effectively.

 

[Splitpi]

Thanks for the input.


What exactly causes the spun bearing? Is it the excessive heat or does it have something to do with coolant hydro-locking the cylinder?

EDIT: From some research it appears to be related to the coolant getting into the oil and then not lubricating the bearings effectively.

Lack of oil... most likely due to coolant in the oil.

 

[03protege]

Its gonna be a ***** if it does need a heater core, talk about pulling the dash ouch lol

Yeah that will be quite the project.

If I was to set the climate control to cool would that also bypass the heater core? Assuming the leak was after the bypass valve.

 

[iceman510]

Most likely not. Most modern vehicles circulate through the heater core at all times (though some may have shutoff valves for improved A/C performance). I don't know for that particular vehicle.

Regarding bearing damage, I would not run the vehicle until you drain the oil pan and check it in case it is coolant contaminated due to a head gasket failure.

 

[03protege]

Most likely not. Most modern vehicles circulate through the heater core at all times (though some may have shutoff valves for improved A/C performance). I don't know for that particular vehicle.

Regarding bearing damage, I would not run the vehicle until you drain the oil pan and check it in case it is coolant contaminated due to a head gasket failure.

10-4 I will bump the oil pan up in priority.

 

[redyute]

Look at the firewall you will see where the two heater hoses go to the heater, disconnect them from where they hook up, most likely be quick disconnect which would require a tool you may not have, you will need to disconnect the hoses and loop them together leaving the heater disconnected, im not sure if I make any sense but maybe if you can post a pic if the firewall is accessible it would be easier to understand. Coolant flows through the heater core all the time so playing with the climate control doesn't help

 

[ed_v]

What kind of car?

You mentioned the timing belt snapped. If it is a interference engine, the pistons could have smashed against a valve causing it to bend. This could lead to overheating amongst other things.

Ed

 

[redyute]

What kind of car?

You mentioned the timing belt snapped. If it is a interferenc

mazda 6 timing chain

 

[ed_v]

mazda 6 timing chain

Ha!

My dog jumped in my lap causing me to hit send before I finished typing that

Ed

 

[redyute]

Ha!

My dog jumped in my lap causing me to hit send before I finished typing that

Ed

Funny u said that mine has been sleeping on my lap all morning lol

 

[ed_v]

The Mazda 6 is a interference engine. That was a timing belt that broke, not a chain. If the water pump and belt has been replaced and it is still overheating, bend valves might be your issue.

As others mentioned, do a leak down test to check for head gasket failure.


I'd still buy it for a dollar!

Ed

 

[redyute]

The Mazda 6 is a interference engine. That was a timing belt that broke, not a chain. If the water pump and belt has been replaced and it is still overheating, bend valves might be your issue.

As others mentioned, do a leak down test to check for head gasket failure.


I'd still buy it for a dollar!

Ed

Incorrect 2007 mazda 6 carries a v6 3.0 ford engine with timimg chain, no timing belt, water pump runs off the serpentine belt.

 

[03protege]

The Mazda 6 is a interference engine. That was a timing belt that broke, not a chain. If the water pump and belt has been replaced and it is still overheating, bend valves might be your issue.

As others mentioned, do a leak down test to check for head gasket failure.


I'd still buy it for a dollar!

Ed

Timing belt/chain is still good, it was the water pump belt that broke.

 

[03protege]

Look at the firewall you will see where the two heater hoses go to the heater, disconnect them from where they hook up, most likely be quick disconnect which would require a tool you may not have, you will need to disconnect the hoses and loop them together leaving the heater disconnected, im not sure if I make any sense but maybe if you can post a pic if the firewall is accessible it would be easier to understand. Coolant flows through the heater core all the time so playing with the climate control doesn't help

That makes sense, are the quick disconnects the same ones as used on a fuel line?

 

[cgall]

Pull the dipstick, if there is water in there it will have bubbles above the "full" mark. I would risk the $100 to replace the water pump, thermostat and belt and fire it up. If bearing is spun, you will get low oil pressure.

 

[Iroc-Z]

If your fixing yourself go for it. Put a new water pump and belt on. Loop heater core hoses and see what happens. More then likely it will be just fine. Then you can attack the heater core. Today's engines can take allot of abuse.