Antifreeze Leak Under Thermostat Housing
#1
Antifreeze Leak Under Thermostat Housing
I recently completed a total overhaul of my 2.0L LNF. I had it stripped down to the bare block and went through everything with a fine-tooth-comb. I was extremely cautious to keep things clean during assembly. However, I seem to have very tiny coolant drippage on the bottom of the bellhousing. Since the engine is back in the car, it's very hard to pinpoint the source. But I dug out pictures from when I removed the engine, to study the layout of the area. See the blue circled area in the attached pic when I had just taken the engine out of the chassis. This is the area where my new leak is, and it appears from the picture that it may have been leaking in the same spot before I disassembled. For the life of me though, I can't see where the leak might come from. If it was the thermostat housing, I would expect the staining to start way up at the housing, but it only appears down low and only on the bedplate and oil pan. And I looked through hundreds of other pictures I took of the engine to see if anything in the lower block, bedplate, or oil pan might be the source of the leak; no dice though. I don't see anywhere it could come from, except possibly the thermostat housing, temp sensor, or turbo coolant line. Is this leak a known issue? Has anybody seen this before and pinpointed the source?
Thanks in advance!
M Ridzon
Thanks in advance!
M Ridzon
#2
There is no reason for coolant down there besides a drip. Are there water journals between the block halves?
The arrow point to the front of the engine, and upside down. The black circles are the alignment dowels.
The arrow point to the front of the engine, and upside down. The black circles are the alignment dowels.
#3
@donbrew no there are no coolant passages between the block and bedplate (i.e., lower block). I was wondering that too, but realized there are none after I reviewed all of my photos from building the engine. Additionally, I remember pressure-washing the bare block and when I stuck the water nozzle in the coolant jacket, nothing ever came out the very bottom of the block where the bedplate bolts on.
#7
I had a leak in a similar location on my 2.2. It was the O-ring on the hard line going into the thermostat housing. From what I read before completing the repair, it is not unusual for that O-ring to get dis-formed and seep. IN my case it got a little worse as the weeks went on. I eventually replaced the O-ring at either end of that pipe, the thermostat, and the water pump while I was in there.
#8
I had a leak in a similar location on my 2.2. It was the O-ring on the hard line going into the thermostat housing. From what I read before completing the repair, it is not unusual for that O-ring to get dis-formed and seep. IN my case it got a little worse as the weeks went on. I eventually replaced the O-ring at either end of that pipe, the thermostat, and the water pump while I was in there.
I have a dozen other pictures of this region of the engine and studied them again. The only thing that seems logical is the turbo coolant return line. It is directly above the location of the drippage. I plan to jack the car up this weekend to change the oil (it will then have a few hundred miles on it). Assuming the leak is still there (but hopefully not; fingers crossed), I plan to study the turbo coolant line very carefully to see if it's the source.
#10
Are you referring to the large diameter pipe (about 2") spanning between the water pump and thermo housing? If so, those o-rings are brand new; I replaced them during the rebuild. Yes, there is a remote possibility that they are leaking. But despite limited visibility, that is one spot I can see pretty clearly. I saw nothing coming from that pipe. I'll certainly check again.