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I have an '03 STR that has a coolant leak spotting on my drive.

Putting the car up on stands, all plastics off, and looking for culprit leads to the front edge of the oil pan.

Remove oil filter to follow trail further, clean front of block and oil pan leading edge. Can see "weep" develop on fasteners holding timing cover (?) to front of motor - behind the big pulley, and at the joint of timing cover (?) to the front of motor.

Again, location is front of motor, directly above oil filter (have to have it removed), above the leading edge of the oil pan.

Any thoughts at likely candidates?

Next steps are to either pressurize the system and see what comes, or to go with the UV dye and black light.....

Thanks for any help.

Kind Regards

 

To see the front better maybe remove the air trunking & box. Thermostat and lots more are in/down there.

Other common places are the header tank and the DCCV but if the latter I think you'd probably have seen orange staining by now.

 

Place the system under pressure and with a small inspection mirror, check around the water pump and thermostat housing.

NBCat

 

Thanks for the feedback....kinda where I was going.

Anyone have any idea what the size is on the t30 torx drive bolts that hold the thermostat tubes to the motor? The ones in the feet of the cast tubes, are they 8mm-1.25 X 20mm long? or are they something different? Gonna get rid of those.....

 

It may be best to diagnose what exactly is the source of the coolant leak and then match up the bolts should they need to be removed.

Depending on their location, the Torx-head bolts are either M6x20 or M6x25.

NBCat

 

Hear you NB, working on it now - limited daylight. Had those particular fasteners in my hands a few days back, didn't like them then, are primary suspects now.

Got home to find my "weep" had left a basketball sized puddle under the car.

Removed airbox and tubes, to see drivers side thermostat housing and foot - to the best of my ability. Unfortunately, seemed dry, or at least no indications of significant seepage/weep - by bare hand feel and visual with flashlight. Have not yet removed the coolant resevoir (again), but inspection again indicates no source.

I have included a picture of the offending weeping fastener.

The view point is from under the car, as if you're lying down, looking up, with your head at the inside of the drivers side wheel.

again, have no idea what this fastener is bolting down, I keep saying "timing cover" only because it seems like it kinda should be....

Any more thoughts would be helpful. Tonite is a trip to usual suspects to source UV dye and pressure tool.

Thanks again for any help.

 

From the photos, it appears that the bolt in question directly above where the oil filter would normally be is one of 24 M6x35 bolts securing the front timing cover to the block. There is no coolant passage near this particular part of the engine, so the leak is from above, most likely from the water pump or thermostat area.

Be sure to also check the hoses for seepage where they join to the various plastic housings, especially if someone has replaced the constant-tension clamps with a screw-type clamp as over tightening may have caused the plastic to crack.

NBCat

 

NB

Thanks for the analysis.

Picked up my dye tonite (not cheap), will hold off pending close examination of the water pump.

I feel good about this one, as it is lower than the t-stat - and since I can feel no coolant leak from the t-stat housing feet, and I've only added one gallon to the system and not primed the pumps by turning on the ignition, the pump seems like a much more likely candidate.

Plus, it's one of the few hoses/rings/clamps/belts I haven't touched in chasing belt squeal (replaced the serpentine and the accessory belts) and coolant leak at back of motor (SC hose - yes, that one), coolant leak at pass side (DCCV), new EGR (just for fun - while a guy is in there). If I hit the water pump, I'll pretty much have all new belts and hoses!

With 115K on the car, doesn't really make me feel too bad to know they're all good for the next 100k.....

I'll let you know how it turns out.

Kind Regards,

 

No need for dye or light - was definitely the water pump.

FYI - picked up the GMB replacement water pump from Advance Auto - was the least expensive, and available, so I picked it up. Didn't know what to expect, but in taking it out of the box, was immediately impressed with the build quality. After taking the OE pump out, I was really impressed with the build quality of the replacement. One of the few times with a replacement part that I felt better about what went back in vs. what came out. The OE pump seems to be a very poor design. Lots of plastic (including the impeller) and judging from mine the plastic "lip" above the rubber ring was what failed - further picking at the plastic had it flaking away in my hand. The $60 GMB unit seemed well put together (metal impeller), was a bit different in design (a 2 piece bolted together casting vs. a one piece OE design), and came with a single metal gasket. Overall, I was pleased. Really pleased with the no leaky-leaky....

Thanks all for the help!!

 

Glad you found the leak! The water pump is a simple replacement on the 4.0 litre engine. Since you will have the cooling system drained, are you also planning on replacing the thermostat as well?

NBCat

 

Did the Tstat (went with the low temp Eurotoys), as well as the gaskets in the feet, and replaced the crappy torx drive bolts with socket head caps, washers, and locks. Goin' no where now.

Check my new thread as the fun (cough cough), continues.....

Again, thanks for your help on the leak issue!

 

I hope it worked out well for you!

NBCat