hi,
i was driving my volvo in, hot, late afternoon traffic yesterday when the coolant levels started boiling over. i took it to a garage right away and they said it's probably either a cracked gasket head or the thermostat. I had them replace the thermostat, and when I was driving home it started to get real hot a few more times. Each time I pulled over and let it cool down. It seemed that the longer I was able to drive it the longer it would stay cool, but if I was stuck in slow moving or stopped traffic then it would boil over fairly quickly.

Just a little background: the car has 200,000 miles on it and last week the heater core died. I decided to have a mechanic bypass the core instead of getting a new one, which i'm fine with. Then I drove it 200+ miles from washington d.c. to new york without a hitch, then this overheating happened yesterday.

I don't know if the two are related. the thing is, I don't think it's a gasket problem because the car doesn't leak anything when it's either running idle or parked. and there isn't any mixing of fluids.

The fans seem to work though I don't know if they are working as long / hard as they're supposed to be.

I'm left to conclude that either I need a new radiator, or a water pump, or a flush - or all three or something else altogether.

Any thoughts?

Thanks.

Sounds like the fan isn't working properly.Did you have the A/C on?
You might have a radiator going bad.

The A/C on the car doesn't work. I don't know why. I took it to a mechanic once and he tested the blower motor, which worked, and concluded it must be electrical, possibly in the control panel / head. I didn't bother to get that fixed. But I think you're right - I mean, unless the dead A/C would negate that possibility.. that it's the fan and / or the radiator. And from what I understand, so long as I drive it not in traffic but rather on long trips when it's relatively cool out I should be ok, right?

I would logically connect the 2 events - as I am a logical person

and as most mechanics are ****** and non logical I would check just how he "bypassed" the heater

I can think of one way which cause the problem, ie diminish water going to rad

bet you a Big Mac thats it

This post has been edited by ampangbear: Jul 18 2005, 08:47 PM

The reason I asked about the A/C is because if the A/C is on the cooling fan will pretty much run all the time.

Most of the time if they bypass the heater core they will just put a hose on the 2 lines and loop the hoses together.Which is fine as long as it is flowing good.

The reason Im thinking fan is because as long as you drive somewhat fast is stays cool.If you are in traffic it heats up.

But if the fan is working good then it most likely is poor flow in the cooling system.

exactly as I was saying above

the heater is in PARALLEL with the rad, but not normally a prob as if you are using heater it becomes a second rad, AND the ambient is cold so no problem that flow is diminished in the real rad

but if you simply loop then say 25% of fluid is simply doing the loop with NO COOLING AT ALL so eg if rad is operating on hot day at 20 deg TD ie OUT is 180 deg and IN [to engine] is 160 deg, then with bypass the IN is 165 SO the OUT goes to 185

sit in traffic for a few minutes and that escalates to OUT = 220 and boil over [even under pressure]

its simple physics - not rocket science

what the dumb **** mechanic SHOULD have done was have a shut off cock in the loop - which was what I did when same thing happened to me [got a cock from a Ford at wreakers yard]

but maybe good news might be its not the core but the thermostat valve sitting on side of the core - these leak if old and you have had overheating so high pressure in system

This post has been edited by ampangbear: Jul 18 2005, 08:51 PM

dpepper,

I would suggest you try the flushing of the coolant first, as it is the easiest and cheapest. :)

Thanks and good luck.

yeah - flushing [ie back flushing] will allow more fluid via rad so maybe only 24% will bypass via the mod by the dumb **** mechanic

it will STILL boil over but :57:

smartest is to FIX the problem ;)

This post has been edited by ampangbear: Jul 18 2005, 08:48 PM

The same thing happened to me yesterday, I accidently knocked the power wire to the radiator fan loose while working underneath the hood, so my car overheated. The same problem with the a/c, when I reconnected the wire, all was fine, and the a/c started working again.

Doctor you are a damn ****...............no wonder your profession is filled with arrogant ********* that "guess" at the diagnosis unless they have an under-paid lab tech confirm the "real" problem through blood work! I mean here your sorry *** is on an auto forum trying to apply the same guess tactic to troubleshoot someones overheating problem via a message board LMFAO! Furthermore you **** "Rocket Science" itself is "simple physics" also. Your logic and reason when coupled with your ignorance will result in the same conclusion in the world of auto repair as it more than likely does in your patients..............un-needed expense and hardship as the result of a bad diagnosis 50% of the time, a close call 30% of the time and a lucky guess 20% of the time............The real shame is that in the medical field this makes for a "good" doctor but in the automotive field it would be un-acceptable.

This post has been edited by ampangbear: Jul 18 2005, 08:53 PM

In this case the "DOCTOR" may have made a lucky guess. It could be a "flow" problem but not due to the bypass hose installed in place of the heater core, though the Doctor would like to believe the Mechanic "messed it up" if anything the bypass hose would allow for more flow by removing the restriction the heater core places on the system. ( The heater core aids in cooling only when using the heat and allowing air to flow over the core and into your interior.....this offers minimal cooling for the engine though) It is very possible that since the reason for a failed heater core is most often caused by the corrosion of its material, the propellers on the water pump have also corroded to the point of uselessness and would not pressurize the system during accelleration. Since they have not invented an X-ray machine for the automobile you would have to remove the water pump to confirm this. In the case of a leaking head gasket you may not notice any external leak if the coolant is leaking into the cylinders and being absorbed into the combustion process, which is the case in most failed head gasket situations. you would or should however notice a white cloud of smoke from your exhaust if this were the culprit.

OK this is now becoming clear

I said



so YOU were the dumb **** mechanic, so bloke took car back to you to fix your mistake and you asked how did he know and bloke said the doc told me so you jumped in to have a say

:trophy: so do I get my Big Mac :trophy:

but more important HAS volvo been restored to health by bypassing the bypass with a non bypass

This post has been edited by ampangbear: Jul 18 2005, 08:43 PM

:offtopic:
PEOPLE!

PLEASE... Members come here to get suggestions on what they should be looking at, when their cars are not in 100% working condition, not to read things like this. :(

Of course, you may give SUGGESTIONS. EVERYONE CAN GIVE SUGGESTIONS. Noone is forcing any idea on anyone. If the members like the suggestions, they may take it up, either with a professional mechanic or if abled, DIY. Everything is afterall on the risk of the owners themselves anyway...



So, if you have an advice or two, GIVE IT!
If you don't want to, then SHUT UP!
But that SHOULDN'T be the reason for us to start messing each other up!



...
...
...



Come on, man!
You guys are a WORLD apart. There's more than a 50% chance that you have not even met. And an equally more than 50% chance that you would never meet... This is not the way we should be greeting ourselves...




P/S:
And I don't enjoy editing other peoples' posts either. So, please....

I agree 100% and thats what I did - the bloke had a problem ie car boiling over and as we know that can be a terminal problem or a very expensive problem as Volvos dont have cast iron heads since about 1970 so one boil over and head warps

BUT this bloke gave a clue and as a PROFESSIONAL ENGINEER it would IMHO have been totally recalitrant of me not to explain the 99% probable problem. He said the problem coincided with what he called a "heater bypass" operation

So as a good engineer I put 2 and 2 together and realised that what the mechanic had THOUGHT to be a heater bypass was in fact a RADIATOR bypass - I then tried to explain WHY in lay terms

And I hope the bloke TOOK the advice and saved poor Volvo from terminal overheating [but I did not hear back but thats cool I am not after praise BUT IF I CAN SAVE ONE VOLVO THEN IT IS A FAR FAR BETTER THING I DO .... etc]

then this Beamer bloke comes in with his AK 47 accusing me of all manner of stuff like being a drunk etc and with some diatribe re medical doctors not doing a proper job

Im not a med doctor buddy - neither is Valentino Rossi - I just use the name as he he does

but at the end of the day I dont even care if I get the Big Mac for being correct - but I would like to hear back that I saved this volvo from Volvoitis Terminitus

This is America buddy..............if a mechanic here says he bypassed the heater core then that is what he did! You miss the point another gentleman as well as myself have tried to make to you..............the mechanic did not create the overheating problem by bypassing the heater core, if anything he temporarily relieved it. Your quest to make this the fault of a "stupid mechanic" is leading you down the wrong path, your desire for this to be the mechanics fault is dissauding you from seeing the obvious fact that there was a problem with the cars cooling system before a heater core bypass was ever performed. The biggest fault of the mechanic was to ever perform the heater core bypass for this person to start with. Honestly if it were me I would have refused to do anything other than repair it properly and charge accordingly.............if the gentleman declined a proper repair for whatever reason I would have charged as much for just "checking" the system as this mechanic probably did for installing the bypass. That is how you avoid situations like this.