When is a leak not a leak?

[SVC-66]

Quick summary - it's an 02 LS8 Sport. I had some leaks taken care of...typical stuff, vcg's, degas bottle, hydr fan pump. It's the hydraulic leak that is annoying me to no end.

I got the car back and there was still a leak - the reservoir for the fan was low. I called the shop, took it in, he looked at it and suggested Lucas stop leak**. Here's where the funny business starts -- from the time I left the shop to hours later when I topped off the reservoir, I noticed no difference in the level. For a few days, no leak. Then it came back so I called the shop - I'm going in tomorrow - and now it seems to be not leaking. So for a few days each it went from leak to no leak to leak to now no leak.

Is there an explanation for any of this? I'm still of the mind that it's the pump - since a new one priced out at $673 we went with used and I trusted him to trust his supplier.

**I've since read a post where a couple people said stop leak screws with the solenoid...there wasn't an explanation in that thread so if someone could tell me, I'd be grateful.

Oh, this is the 2nd shop with a good reputation that suggested using Lucas stop leak.

 

[SVC-66]

I'm an idiot. It was the fan that was replaced, now it's the pump leaking. Still don't understand why the leak seems to appear and disappear.

Can someone explain what stop leak does/can do to the solenoid?

 

[joegr]

Leak stop works (when it works) by sealing up small holes or passages to prevent fluid from flowing through.
The solenoid fan speed control opens and closes small passages for fluid to flow through. The potential problem seems pretty clear. I think that trying the stop-leak was a big mistake. I hope that you don't end up with fan problems as well as pump problems.

Parts expand and contract with both temperature changes and pressure changes. Temperatures and pressures will change with operating conditions and environmental conditions. Your leak may only occur at certain combinations of conditions.

 

[SVC-66]

Leak stop works (when it works) by sealing up small holes or passages to prevent fluid from flowing through.
The solenoid fan speed control opens and closes small passages for fluid to flow through. The potential problem seems pretty clear. I think that trying the stop-leak was a big mistake. I hope that you don't end up with fan problems as well as pump problems.

Parts expand and contract with both temperature changes and pressure changes. Temperatures and pressures will change with operating conditions and environmental conditions. Your leak may only occur at certain combinations of conditions.

Yeah, crystal clear. (sorry, I saw the big courtroom scene from "A Few Good Men" a couple nights ago). There's been a lot going on lately...I don't like it but sometimes the simple stuff gets by.

Thanks, joegr, I appreciate it. I'm thinking I should have him drain the system (as much as possible, anyway) and then fill with straight Mercon V.