92 coupe - LT1 w/A4. All original engine parts with 110K.

I'm having this coolant leak issue. Once I shutdown the engine it leaks some coolant. Somewhere down the front of the block. It collects under the engine on the brace and leaks to the floor. About 4-8 ounces. Some days less. Once it cools down no more leak until after I run it again.

I've checked the hoses. The water pump doesn't appear to be leaking out of the weep holes unless it only does it during cooldown. I can't really tell about the water pump gaskets as it's a pretty tight area. I stick my hand all over the front of the engine and no coolant. There is no oil in coolant or coolant in the oil.

Is there something other than the water pump on the front of the engine I should be checking? I'm a little lost on tracking this down.

Thanks for any ideas.

Graham

 

Does your engine have coolant hoses that go to and from the throttle body?

What about the two sensors at the front of the intake manifold? the 86 has two so I'm guessing your year has them too.

How about the thermostat housing?

Jake

 

Possibly leaking around the intake manifold gaskets where they seal the coolant port at the front of the heads? I've fixed a similar problem on my L-98, leaking coolant at both ends of the manifold. Most likely it was actually only leaking past the bolt threads (some "mechanic" before me had failed to use sealant on the manifold bolts...) , but by the time I got to it the gasket was junk too....

 

Ok I'm still stuck. I bought a cooling system pressure tester. The leak will only happen when I get to about 10lbs of pressure. Radiator, heater and hoses are all good. Put my hand under and around the water pump. No leaks. Weep hole is bone dry. Checked the freeze plug on the passenger side, dry. Can't see the one on the drivers side cause there's too much crap in the way...

When I get under the car and set 10lbs of pressure I see the coolant driblling down onto the arm that the monoleaf sits in. Looking up with a flashlight it looks like it is coming out of the front lip of the oil pan or just above it. Since I have no coolant in the oil, no white smoke or anything like that I'm discounting cylinder heads and intake manfiold. I've gone all around them and no coolant shows. Somewhere on the drivers side of the front of the engine appears to be where the leak is. Short of pulling all the accessories off the front of the engine I can't see much in that area.

What am I missing here. Besides the water pump and the intake manifold passing coolant what else in the front would do this? I'm lost now...

Thanks for any help you can offer.

 

The only other thing would be the upper rear portion of the water pump. Once the system has pressure a very small pin-hole size leak can force a stream of water upwards or to the side. The drivers side water pump to block gasket would be another area to look at. The driver's side freeze plug is another possibility but that's pretty far outboard of where you are seeing water. But again a little pressure in the system can cause a leak to spray out in different directions.

All of the accessory stuff on the driver's side is somewhat tedious to remove but it doesn't take too long to get to where you can see that part of the pump where it attaches to the block. Disconnect the battery, remove the serpentine belt and pull the alternator, remove the bolts holding the A/C compressor and slide it out of the way.

Remove the belt idler and remove the 4 bolts holding the PS pump to the bracket and move it forward. BTW, once you do all of this, the plug wires on the driver's side are exposed and could be fairly easily changed if you want to do this now.

In any event, you DO NOT want water to get on or in the OptiSpark unit. Water will ruin it and you'll be looking at hundreds of bucks to replace it.

 

The 92 has 2 brass coolant air relief bleeders. 1 on the thermostate housing and 1 on the bottom side of the throttle body. Be sure the brass screws are both tight.

 

Check if you have an oil cooler. those are buried under the block on the drivers side. 5/8 heater hose from and two the Oil filter housing.

 

Bingo. Do I feel like an idjut... 2 of the 3 bolts on the drivers side of the water pump were not tight enough. They've apparently loosened over the years. The passenger side was nice and tight. So I made sure they were all torqued to 35lbs. Drivers side was probably 15lbs or so. Once I got them tight leak went away It was streaming down the block and over the front lip of the oil pan. The Opti, plug wires, and all accesories are nice and dry.

We'll see if I haven't messed up the gasket after I take it for a good drive tomorrow. Either way this winter I will replace the opti, water pump, ps pump, and plug wires. I just replaced the high pressure ps pump hose 2 weeks ago. Now that was a fun chore...

Thanks, Graham

 

Jake