Overheating help needed please. 97 318ti

[radicalr6]

I have an 97 318ti that overheats at random times. Im not sure what to do anymore. It started after changing the radiator.
The car will drive alright for a week or so then the hose that goes under the manifold broke. So I had a shop change the hose. After, the car was fine for another week or so then it overheated again. I thought the shop did not flush properly, so I flush the system, and it worked fine for another couple of weeks. Then it overheats again, and I changed the thermostat and fan sensor. After driving for another week, it over heats again.

-I thought it could be the head gasket, so i let the coolant cap off, revved it to 3.5k and it seemed fine, no coolant flying out.

-At this point I am stumped on what the issue can be. Can someone please direct me in the correct path. It is the most annoying car issue I have ever dealt with.

P.S My secondary Air Pump needs to be changed.. Could that be an issue?

[teetime4one]

There's a thread about properly bleeding the radiator. If you do a search you will find it. That is where I would start. Also, keep an eye on the level of fluid in the expansion tank.

[radicalr6]

Originally Posted by teetime4one

There's a thread about properly bleeding the radiator. If you do a search you will find it. That is where I would start. Also, keep an eye on the level of fluid in the expansion tank.

its been bled and flushed couple of times. When Idling there is no issues. And even when driving there is no issues, it will just randomly start to overheat. check the spark plug well, there is some water in the 1st and 2nd

[cooljess76]

Originally Posted by radicalr6

its been bled and flushed couple of times. When Idling there is no issues. And even when driving there is no issues, it will just randomly start to overheat. check the spark plug well, there is some water in the 1st and 2nd

Yeah, but have you bled it properly?

http://www.318ti.org/forum/showthread.php?t=27983

BTW, STOP OVERHEATING YOUR CAR.

[radicalr6]

Originally Posted by cooljess76

Yeah, but have you bled it properly?

http://www.318ti.org/forum/showthread.php?t=27983

BTW, STOP OVERHEATING YOUR CAR.

I have bled the car properly, I have had it to my BMW mechanic as well. I am stumped as to what the issue is and so is the mechanic.

-Here is the latest info. Checked the spark plugs 2 weeks ago, and there was water/oil in the 1st chamber. Replaced the plugs and cleaned the chamber. Car drove fine for two weeks and this morning started to overheat once again. Car does not overheat in idle. There is no smoke from tailpipe, there is no milky residue under the engine cap, had the expansion tank cap open revved the engine till 3500 and no explosion from the tank...
Any help is appreciated.

Have put in
-radiator
-thermostat
-fan sensor
-new expansion tank cap
-hose under manifold

[zoner]

Originally Posted by radicalr6

-Here is the latest info. Checked the spark plugs 2 weeks ago, and there was water/oil in the 1st chamber. Replaced the plugs and cleaned the chamber.

When you say "water/oil in the chamber", do you mean inside the cylinder- like, water/oil on the end of the spark plug- or is there water/oil in the plug well (outside of the cylinder)? Water in either place leads me to believe that you might have a cracked cylinder head. The more you continue to overheat it, the more likely it is that you have a cracked/warped head and/or blown head gasket. Also, have you checked to make sure that the fan is turning on once the engine heats up? Replacing the fan sensor likely eliminates that as the culprit, but there's also a fan relay, fan fuse, the fan itself, etc.

[radicalr6]

Yes it is outside the chamber in the plug well. Yes, after car idles for 10 min or so the fan comes on.

I just dont understand why after I flush the car I can drive for a week or so then it overheats. I was thinking of a head gasket, but why it wont overheat everytime I drive..

-Is the waterpump a possible culprit?

[zoner]

First and foremost, you need to figure out where that water is coming from- that is likely the source of your problem. If you've dried that area out and the water reappears, you likely have a cracked head, as there are no water hoses or components of the cooling system that would fail and leak water into that area. Good luck!

[radicalr6]

Originally Posted by zoner

First and foremost, you need to figure out where that water is coming from- that is likely the source of your problem. If you've dried that area out and the water reappears, you likely have a cracked head, as there are no water hoses or components of the cooling system that would fail and leak water into that area. Good luck!

Will check that ASAP! Thank you

[radicalr6]

Originally Posted by zoner

First and foremost, you need to figure out where that water is coming from- that is likely the source of your problem. If you've dried that area out and the water reappears, you likely have a cracked head, as there are no water hoses or components of the cooling system that would fail and leak water into that area. Good luck!

Just checked the plug wells, no water or oil. In the second well, there is a tiny bit of oil, but just an insignificant amount..

[cooljess76]

It often takes several tries to get all of the air out of the cooling system. If air builds up, you'll develop vapor lock and the coolant won't circulate through the radiator. What's your bleeding technique?

[radicalr6]

Originally Posted by cooljess76

It often takes several tries to get all of the air out of the cooling system. If air builds up, you'll develop vapor lock and the coolant won't circulate through the radiator. What's your bleeding technique?

Put car to ON, have heater on hot and on. Remove bleeder screw slowly add water until no more bubbles are seen while massaging upper/lower hoses...

[cooljess76]

Cool. It also helps if you park the car on ramps or an incline so any trapped air will be forced up and out of the bleed port. Once the engine reaches operating temperature, you should feel the radiator hoses pressurize and perhaps you might be able to feel if coolant is flowing through it. This will help you determine if your water pump is functioning. Although I've never tried it, it's been recommended to me to use a product called "Water Wetter" by Redline. It's supposed to lower the surface tension of the coolant/water allowing it to circulate better and relieve itself of air bubbles easier.

edit; this may seem like a dumb question, but when you say "put car to ON", you mean the engine is running correct? Obviously the engine needs to be running to spin the water pump, otherwise coolant won't circulate.

[jca]

I recommend Water Wetter, too. I would throw in a bottle ($10), let it warm up and mix, then bleed again and see what happens. Unfortunately, my recent overheating problem turned out to be a headgasket. Good luck with a fix.

[radicalr6]

Originally Posted by jca

I recommend Water Wetter, too. I would throw in a bottle ($10), let it warm up and mix, then bleed again and see what happens. Unfortunately, my recent overheating problem turned out to be a headgasket. Good luck with a fix.

How to tell if its the head gasket?