coolant smell but no visible leak

[funcrew]

My stock M20B25 with 64K miles runs absolutely perfectly. I just went through and replaced the water pump, both halves of the thermostat housing, thermostat, all the big hoses, and the cracked radiator. The engine now smells strongly of coolant when it has been run warm for a while. I can't say if it smelled before, because I did this work as soon as I acquired the car.

Running a pressure test at 16PSI (requiring a BMW-specific adapter that cost almost as much as my old Stant kit) with the engine off and cold shows pressure VERY slowly bleeding off; I mean 2-3 PSI loss over an hour or so, then will hold 11-12 PSI until the next day. There are no visible drips, squirts, etc and no dripping from anywhere under the car onto the ground.

So, a head gasket leak is possible - any other options? Would the throttle body cooling passage cause this, and do those fail very often?

I just did the timing belt & would like to not do the head gasket until I rule out all other possiblities that are easier to fix.

Oh, by the way, in 2 months of daily driving, the coolant level in the reservoir has not gone down by a quarter inch, if that. Engine runs cool and strong.

Any ideas? Thanks!

[Devil Inc]

To rule out the TB warming gasket, which go bad occasionally, you could close off the circuit to and from that point & retest. I don't have it conected on mine, it's only there to warm the TB up, in case it is frozen from sub-zero weather. Plus if you block it off you allow cooler air in to the engine, maybe allow and extra pony or two. Mine also smells of coolant with no visual leaks, so could be normal, I guess.

[jlevie]

Is the smell from the engine bay, or in the cabin? If the latter, the heater core is a possible cause. In the former case there's a leak somewhere in engine bay.

[StereoInstaller1]

My stock M20B25 with 64K miles runs absolutely perfectly. I just went through and replaced the water pump, both halves of the thermostat housing, thermostat, all the big hoses, and the cracked radiator. The engine now smells strongly of coolant when it has been run warm for a while. I can't say if it smelled before, because I did this work as soon as I acquired the car.

Running a pressure test at 16PSI (requiring a BMW-specific adapter that cost almost as much as my old Stant kit) with the engine off and cold shows pressure VERY slowly bleeding off; I mean 2-3 PSI loss over an hour or so, then will hold 11-12 PSI until the next day. There are no visible drips, squirts, etc and no dripping from anywhere under the car onto the ground.

So, a head gasket leak is possible - any other options? Would the throttle body cooling passage cause this, and do those fail very often?

I just did the timing belt & would like to not do the head gasket until I rule out all other possiblities that are easier to fix.

Oh, by the way, in 2 months of daily driving, the coolant level in the reservoir has not gone down by a quarter inch, if that. Engine runs cool and strong.

Any ideas? Thanks!

Mine was almost exactly like this, maybe a bit more loss of coolant, but not much.

Then, one day I was driving along (NOT on my way to band camp) with the heater blasting. All of the sudden, my right foot was very wet and very hot.

All of the windows fogged up, all of them, instantly. Oh yeah, coolant light came on, too.

So, new(er) heater core and control valve later, all is good. No more smell, no more coolant loss.

HTH!
Luke