I had a small overheating problem with my BMW'97 - 316i.
After about 30 minutes drive, I can smell something burning from the engine (temprature level is still in the middle range though), coolant level drops, and the radiator hose are stiff.
I was told (by a panelbeater) that the hoses aren't suppose to be stiff, it should still be squeezeable as when the engine is off. He also said that the overheating problem might be in the engine. & not the radiator , is he right?
Thanks in advance.... &
If you'd like to see the full story, read below :-):
A week ago I had a small rear bumper accident, wasn't that bad just a small dent.
A few days after the accident, when I was driving I noticed the engine temprature gauge reached the red level, but just when I was about to stop , the gauge miraculously back to half way mark, so I thought it must be just an error with the gauge or somethin. The next day it happens again, and again after reach the red for about a minute, it drops back to the normal level.
On the third day, it reached the red zone.. but this time I smell like something burning so I stopped and check the engine.. it smells like something burning & and there's a whizzing sound. I waited for a while for the engine to cool off and then went home, checked the coolant.. and found it's empty & refilled it. THe day after.. still the same problem, when I check the coolant level it drops .. but I can't see any dripping on the floor.
Bcoz of the accident, i brought my car to a panelbeater, and also told him about the overheating problem. When he tried to check, he tried to squeeze the upper radiator hose, and it was stiff. He said it's not suppose to be stiff. He said he'll check the radiator for me. He said no sign of leaking, and he said when he runs the engine for a while, the engine heats up.. end of story..
hopefully the long story helps your diagnosis :-)).. thanks heaps....
Before I say anything I should say I have no familarity with BMWs (only just bought one myself),but being a car mechanic for 10yrs+ I have some idea :wink
Btw you should of checked the coolant level the 1st time it hit the red
Anyway ,it sounds like it could be the headgasket has gone ,if so ,combustion pressure is making its way into the cooling system (hence the stiff hoses) ,when you switch the engine off the coolant is then probably making its way into the cylinders through the same route,(hence the coolant drop without puddles on the floor).Is the engine sometimes slow to turn over?
If you run it with the expansion tank cap off (& cold engine to start!) can you hear/see bubbling?
The temp gauge hitting red then dropping could be because the coolant level dropped below the level of the temp sensor (I dont know where they are on BMs yet) ,did the heating go cold?
I'm afraid ,so far as I can tell anyway, that is no small overheating problem you have! .Don't keep driving it around like that & get it checked out rapido
Take what he said with a grain of salt..... Please!
From what I've read... it sounds like one of two things.. or both... your water pump is going on you... or your thermostat is sticking at times....
Reason behind this... the pressure is building up.. due to the heat of the coolant/water and the pump... and the stiff hoses from the pressure because the thermostat wont open.. its sticking... and then when you slow down.. the pump is also slowing down... thus decreasing the pressure and letting that thermostat open... and circulate the fluid... I've seen thermostats not open on warm up... but open on cool down... its just due to the way that sucker opens and closes... its odd.. but I've seen it happen...
Take your oil cap off... if you have a white milky looking residue... then you pretty much have a head gasket failure... you can also do a compression check... <-- do a search of google if you dont know what that is... .
Best thing to do.... take it to a shop.. and see what they can find out... unless you are a mechanic.
Thanks a lot everyone for your input .. it really helps a lot.. I'll bring it to a mechanic on Monday.
oh another thing that I found out this morning, when I started the engine from cold.. the car was rumbling, then I turned it off, for 2-3 seconds, and turned it back on.. it's ok... I'm not sure whether it's coming from the some problem, or a different problem.
expansion tank <--> is this the coolant little tank/container ??
If I start the engine from cold, I can't see any bubbles or hear bubbles.. I can only see water dripping from the small hole INSIDE the top part of the coolant container to INSIDE the coolant container itself.
I also check the engine oil cap, I couldn't see any white spot or other funny colours, just a dark oil colour.
any clue ?? could it still be a head gasket problem ?
Take what he said with a grain of salt..... Please!
How can you be so dismissive when you haven't looked at the car either???
Nor do I think your sarcasam is nessacary or a good example for a moderator to set!
You could well be right that the thermostat is sticking (though that doesn't explain the coolant loss) ,also unless BMWs have their thermostats in a wierd place (like after a hose!) then the pressure generated by the coolant pump would not reach the main hoses so it doesn't explain the stiff hoses either.
Though your idea does tally up with the temp guage readings he's getting.
If the water pump had gone their wouldn't be a sudden drop in temperature as it neared the red,it would stay hot whilst running (assuming there's coolant left)
Bearing in mind that a panel beater told you the hoses were too stiff this maybe a red herring (we don't know his experience here).
If they feel moderatly stiff then this could be just normal pressure generated by the engine.
If they are rock hard & barely give at all then it could be the head gasket
Btw you can have a blown head gasket & have no milky residue ,it depends where the gasket has blown (if it has).
In my experience, & from the limited information you were able to give us ,I still think it could be the head gasket ,or it might be the thermostat sticking and you have a coolant leak which hasn't yet been spotted.
And yeah expansion tank= coolant tank
As for the rumbling ,no idea ,you didn't say where from so it could be anything.
Anyhow ,I'm sure your mechanic will do a cooling system pressure test,cylinder compression test & any other test he needs to diagnose it :wink
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