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Leaking on top of thermostat housing. 1.8l

8438 Views 2 Replies 1 Participant Last post by  ralph1981
So about 8 weeks ago I did a coolant change using the Valvoline Dexcool. Flushed using lots of distilled water

Now there is obvious leaking on top of the housing and from the build up on one spot, to me looks like plastic plug that connects to some pipe or electrical harness which itself goes somewhere behind the engine past the fuel injector rail.

See image...that base of that thing standing in the middle, thicker build up.

In the last week, checking daily I have not observed wet spots. The coolant has dried up earlier and left the brownish red Dexcool ingredients behind. The coolant premixed in the bottle is very strong in red colour.

No coolant smell, ever and the reserviour is half full and has stayed like that for over a month.

Shortly after the coolant change, I added the another dose of a stop leak product that uses Liquid Glass and Kevlar because of coolant dripping after I parked the car, which I added to the previous green coolant also to treat a leak from the water pump. I never noticed dried up green coolant in this area before but maybe it is because it does not stain like the Dexcool does.

If the stop leak fails and the problem returns, do I have to install new thermostat housing or can that vertical plug thing be replaced alone?
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I may have answered my own question. Should have thought of this earlier, but I will be cleaning off that stain and see if it comes back.

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I replaced the thermostat to throttle body pipe. Aftermarket one has plastic for the pipe and the old one only seemed to have a shrunken O-ring on the thermostat housing connector, it was flush with the pipe plug & clip part. Replacing the O-ring would have been the better option.

So at 65k miles, I think that is the likely problem, the O-ring. Snapped plug tips happen on higher mileage engines and that is when you must change the pipe.

When changing the pipe you can do it without draining coolant. Do it when the engine is cold, and put a rag under the throttle body pipe connector so that it covers the serpentine belt pully and alternator. Otherwise the small amount that leaks out when you unplug it will contaminate both.
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