chaadster

Hi All,

I'm hoping that someone can provide me with a tip as to possible sources of what appears to be mixed coolant and oil dripping from the front of the engine.

I've searched the forum and found some tips on coolant sources, but nothing on mixed coolant/oil leaks.

There isn't anything visible from the top of the engine bay, but I'm going out to jack the car and pull the trays now. I've not looked under there before, so if there are any common trouble spots I should look at, I'd appreciate a heads-up!

Thanks everyone.

heinrich

Look at the area under the shaft of the water pump - with covers on if you see coolant coming from under the centre cover that may indicate failed water pump. How much is dripping? is the coolant mixing with oil that is pooled on the oil pan from a different leak? Also a common coolant leak is the t-bone thermostat housing, at the block by the oil filler.

chaadster

Thanks for the reply Heinrich,

It's a slow drip, probably less than 6oz. overnight. The two substances could be mixing from separate leaks, but they did start simultaneously. The water pump has that conical protusion, right, on the left side of the engine? Sorry, newbie here...

heinrich

Harder to explain when you have it all closed up. The water pump is the flat metal surface to which your spark plug wires are attached via an anodised bracket which holds your wiring harness at the bottom of the bracket. Sits just under the oil filler. Not important anyway, look under the car and see if the fluid is coming from under the black covers towards the centre of the engine. If so look up top if you see any leaks there. This doesn't sound like anything serious but could be.

You pretty much have to figure out where the drips are coming from. Try to post where exactly in relation to the crank (thing at the centre of the orange wheel) the drips are.

SteveG

Well, I'm hoping it isn't head gasket. Oil shows up in the coolant, or visa versa, will have changed color. You have oil cooler lines to the rad, mine enter on lower right of rad, can leak inside rad, but then how/where is oil coming from? We need to know physical position under car of the puddle, hard to tell w/o removing splash pan. H20 pump usu leaks only coolant. Don't want to know how it could leak both at same time.

Mark

Does the dipstick and coolant resevoir show a mix also?

chaadster

Thanks guys,

Here's what I know now, having pulled the engine trays off.... It looks like the leak is probably just coolant, judging from closer inspection. It was probably just washing oil residue off as it ran down from, well, wherever it's coming from.

It looks like the leak is originating from behind the left (drivers) side timing belt cover. What's back there? Is there any way to remove the cover, partially, perhaps, without removing the belts and pulley system?

There does seem to be some oil pooling in the valleys on top of the engine, behind the thermostat housing, too, but there is no sign of coolant there, nor is there any sign of major oil leakage, so for now, I'll just focus on the coolant.

Any tips on where to go from here?

Garth S

Any coolant from behind the covers - and dry on top, gets a good vote for the water pump seal. so, what to do ....
Drain the rad, remove the top right rad hose, ign. wires, cap and cover ( as if about to check the TB tension). First, check the edges of the TB. Then, with a good focused beam, look for green/orange/ whatever colour coolant tracking from beneath the water pump pulley ( it is driven by the back of the TB, the pulley is often a znic-yellow, ~3" diameter). Check first, talk later ...

chaadster

Cool... thanks Garth... will do.

I'll post my results soon.

chaadster

Uh, well, two things... First, I wanted to double check that the leak was originating from behind the left (driver's) side TB cover; it wasn't leaking, so I ran the motor, and it started streaming pretty heavily. Whatever it is, it has degenerated very quickly!

Secondly, I looked over procedures for TB checks and replacements as prep for sussing out this probable water pump seal problem, and honestly, it looks like more of a job than I can really take on. In short, it's going to the shop! I'll let everybody know what they say.

Garth S

If coolant is squirting like that - may as well disconnect the battery to keep anyone from starting it: tow truck time .... because, until you know more, don't risk slipping a timing belt.

Tails

Chaadster.

Sound like you have a cooling or heater hose leak, if not the water pump seal.

Water pump seal usually start with a small weeping leak unless you have a total seal failure. I have never experience a total seal failure, so I would look at it being a heater or cooling hose.

As you mentioned you can hear the water/steam hissing and it could leaking in such a position that the steam is condensing on the block and running down behind the the TB cover.

If you have a heater hose leak at the centre front of the engine it can be where the heater hose reduces from 19 to 16 mm hose. I have had leaks from this area in the past and it has been caused by the jublee securing clip cutting the heater hose as it has been too tight. There is a valley just below this at the front of the engine and it accumulates oil leakage for spillage from the oil filler and breather hose connection and if you get a coolant leak you could be getting the oily water mixture.
This can overflow and pick up some oil from around the front of the engine. As the sump pan protudes forward of the block the water/oil may give the appearance of coming from the LHS.

A simple way to find a water leak is to pressurise the the cooling system by using an bicycle inner tube with the valve connection. Tie off one end of the tube (seal it off) and then place the other end over the expansion tank opening after blocking off the overflow tube by inserting a small wooden plug. As pencil should do the trick. When all ready pump up the pressure in the system using a bicycle pump and then check for the leak as the engine is cold there should be no problems with scalding yourself.

Hope that this is of assistance.

Tails 1990 928 S4 Auto

chaadster

Okay update time (thanks Matt, I'd forgotten!)...

Well the guys at the shop said my radiator was leaking from the left-hand side, and wanted nearly $2k for the job, which I, uh, don't have. I checked around with the Big 3 and found that I could get a 12 month warrantied rebuilt from 928 Int'l for $600. I went back to the shop and asked them about working with a rebuilt. They checked their sources and came back with a $750 unit with a 3 month warranty.

I figured that I could R&R the radiator myself pretty easily, and the extended warranty would be good, so I decided I'd do the job myself and went to pick the car up four days later. The guys at the shop offered to top up the coolant for me so I could get home, saying that it was leaking pretty badly, but when we out to where it was parked, there was no coolant on the ground and the reservoir was full!

So, I've been driving it-- leak free-- for almost two weeks now. What gives? Could it have been the sudden temp shift (warm days dropped to some near freezing nights when the leak started)? It's been chilly lately though, too. I was thinking that the guys at the shopped tightened something up after checking it out, but why then would they say the radiator was leaking?

I figure I'm running on borrowed time here in any case, and so plan to do the radiator replacement once I put it up for the winter. Anybody have a good a write-up on the job?

Thanks Rennlist!

chaadster

Oops, I forgot to thank Tails for the cool tip on pressurizing the system! Neat trick!