Ok, my 99 4.0l 4x4 was leaving its mark in coolant from time to time, I took it in for a pressure test expecting for a new water pump to be in order since the truck has about 170000km or just over 100000 miles. My mechanic who I trust said that the timing chain cover is causing the leak, likely caused by a timing chain that is close to failing. This repair quote is obviously a little more than I was expecting but I am going to give him the go ahead for a new chain and cover as well as a pump (since he has it apart). Has anyone else had this happen? Does this sound leggit? Can I expect that my engine has been damaged by coolant contamination (I never noticed any significant loss)? Any other parts to be changed while he is in there?
Thanks for any thoughts.

 

You say you didn't notice any significant coolant loss but yet the truck was "leaving its mark in coolant". Those two things seem to be at odds. What do you mean by leaving it's mark? How did you know coolant was leaking - did you find puddles of coolant on the ground? What type of coolant leaks are we talking about, internal or external?

An which part of the front cover is/was supposedly leaking? Was your timing chain assembly making any noise prior to this?

 

When I say there was no signigicant loss I meen that I only added a little coolant to the resevoir to bring it up to level. The amount on the ground was failrly small. I would say that this was a small leak when I looked under the truck I could see that it was tracking down from the front of the engine and dripping from the oil pan. The oil showed no signs of contamination that I could tell. My mechanic indicated that the timiming chain caused this and given time would fail. I never noticed any unusual noice from the truck, the truck always had a subtle ticking sound at idle but I figured that to be typical lifter noice. Thanks.