Chrysler Repair: 95 Lebaron GTC: 3.0L V-6 coolant leak, lebaron gtc, crankshaft pulley

Question
QUESTION: Hi Roland,

I have a fairly serious coolant leak in my 95 Lebaron GTC 3.0L.  I am able to see the water dripping off the top lip of the oil pan at the right rear of the pan, but can trace it to no other source.  The drip starts immediately on starting the engine but then goes away as the engine gets hotter.  It begins again as the engine cools.  I changed the oil and can find no indication of water - I don't think there's anything wrong with the engine.  Could it be the water pump -which if I am correct is located just above the right rear corner of the oil pan?  Thanks very much,

Paul Hudgens
Denver

ANSWER: Hi Paul,
The water pump is located at the front of the engine block so if it is leaking at its front seal it tends to wet the front lower edge of timing belt cover behind the crankshaft pulley.
The water returns to the water pump by the large horizontal pipe that runs from the rear of the engine toward the front in a channel between the cylinder heads and under the intake manifold. That pipe is in two pieces and has two gaskets: one at its tip where it enters the back side of the waterpump and one between the two pieces. At the front end there is a small by-pass pipe to the thermostat housing.
So it may be that one of those two gaskets is leaking and the water then flows out the rear of the engine. There are brackets on the pipe halves that hold it in place which might have a loose bolt. According to another owner at Yahoo Chrysler Lebaron Club group it is possible to remove that entire pipe so as to replace a leaky gasket without having to remove the intake manifold. You can find the posting at http://autos.groups.Yahoo.com/group/thechryslerlebaronclub
and look up message #36436.
So take a look at those two possibilities and let me know what you find.
Roland


---------- FOLLOW-UP ----------

QUESTION: Thanks very much for your help.  I am realizing now that changing the water pump would be a bigger job than I imagined.  Before I do that, perhaps you could verify for me whether or not it is likely that as the engine warms, ie as the metal parts expand and get tighter, that the water pump would stop leaking.  That is what we are seeing in this situation.  Thanks again.

Answer
Hi Paul,
The water pump itself leaks from the front of the pump where the seal around the shaft that connects the sprocket to the internal water impeller wears out. That usually leaks more when the engine is hot because it is under pressure as the system is designed to pressuize with the increase in water temperature. I have not experienced a decrease in water pump leakage with increase in system temperature for that reason.
That is why I suggested that the o-ring seals, which are replaceable, would be more suspicious. Differential expansion of the pipes and joint interfaces might well cause a decrease in leakage at such an o-ring seal as the temperature rises. Particularly because you seem to imply that the leakage is coming from the rear of the engine would this theory seem more plausible. The front end of the pipe that I described does join with the rear of the waterpump, but that would not require the removal of the water pump for replacement of it but rather the o-ring or the pipe (if corroded), doing this from the rear of the engine rather than taking off the front timing belt cover, belt, etc necessary to replace the pump. Nonetheless, it is not a simple job to pull the pipe and replace the o-ring(s), so that is why I mentioned the posting at the Yahoo group.
Another consideration however would be the condition of the timing belt. That can be inspected by removing the timing cover on the upper front of the engine, at the front of the foward cylinder bank. If the belt has not been changed for 100,000 miles then doing that and the water pump and its rear o-ring to pipe joint is an equally plausible approach.
So those are the factors to consider. Why not begin by checking whether the bolts that hold the pipe to the engine are tight and assess the likelihood that what I have theorized about an o-ring leak is indeed the case?
Roland

Roland