Bonton

Friends,

Car is doing well overall. After doing the water pump, TB, new radiator and new fuel lines I drove the car from Austin to Houston and back - a good shakeout - did fine. The temperature gauge stays where it's supposed to be - under the second white line.

Before leaving for the shakeout trip to Houston and back (334 miles round trip), I added maybe 4 oz. to the coolant reservoir. Drove it there and back and didn't loose any coolant. I mentioned this to my mechanic and he thought that it possibly was a little low from air bubbles. Seemed plausible in that case.

Today while driving I got into some stop and go traffic, a bit later I began to smell coolant then the coolant level light came on. The smell continued then went away. The temperature rose slightly but stayed just below second line.

I turned on the fan and did not smell coolant coming from the vents. After reaching destination I got out and looked for leaking coolant. I did not see any at all, no drips. The coolant reservoir was definitely low so I added coolant.

I added 10-12 oz of coolant today and checked the dipstick for any evidence of water-none.

So my first thought was the heater core...What do you guys think?

MainePorsche

Check the 'V', the section under the manifold at the moment you smell it. It will evaporate quickly with the heat there. If you dealt with the fuel lines/fpr, you may have loosened the fpr bracket bolt which goes into the water jacket and holds down the plate gasket at the back of the engine. This can result in coolant loss without a puddle.

Add: Same applies for the bolt that holds down the dampener bracket on the other side.

Add: gasket 15, bolt 19 on the Right side.

Bertrand Daoust

+1.

Mrmerlin

I would guess its your heater control valve and short hose that needs to be replaced.

otherwise is the coolant bottle tan or brown or does it have any cracks or does the cap fitting have crusty deposits? might be time for a new coolant bottle.
Was the coolant cap replaced?

Beyond a loose hose clamp on the water bridge or radiator look at the HCV and short hose .

Usually the radiator will leak at the top of the inlet but since you swapped it then it should be leak free

Landshark87

That's where my leak was. I was monkeying with the valve trying to ziptie it closed, and on my next drive I got burning coolant smell and coolant light. No evidence of any leaks around valve or the short hose, just on the garage floor.

Replaced with new valve and short hose, so far so good.

StratfordShark

I'm firm believer in the "what did you work on last" principle of troubleshooting.

Like you I changed radiator recently, so have a confession to make.

I started losing coolant at rate of about a litre every 100 miles, but I couldn't see any signs of leaking coolant in engine bay. But I did spot a little damp patch below spoiler at the rad drain side (the coolant had run along bottom of spoiler from that side)

Wasn't rad drain though. I had also fitted brand new top and bottom hoses, and squinting under car could see coolant drops where lower hose is clamped to rad. I hadn't tightened the lower hose sufficiently! I don't like over-torqueing hose clamps so they cut into hose, and I think the new hoses softened slightly with heat. At any rate it was sloppy work by me, fixed with another turn or so on the clamp.

Make sure your bottom hose is tight, as if you lose coolant there it won't be obvious.

Bonton

Friends,

I believe I've found the source of my leak. It is at the firewall where a coolant hose attaches with a band clamp to a metal line on the firewall. This line runs from the metal line at the firewall to just forward of the reservoir and into the inner fender. Where does it go? Does it meet the backside of the reservoir?

So I took told band clamp off completely and replaced it with two new clamps as the metal line is so far into the coolant line. Left the airbox off and took a sprited ride. Soon the COOLANT light was on again....I pulled into the driveway and looked down into the bay at the passenger firewall and saw that it was wet again but was not spewing out....I was expecting something more spectacular. So my fix didn't work.

So here is my next approach. I'll cut the line off of the metal line at the firewall, install a new hose and splice it into the remaining original hose using a brass union. Sound like a good approach. I guess the other approach involves removing the whole fender in order to get to where ever the hose goes....

Any help or tips appreciated here, i don't know why the connection continues to leak, maybe it's got a split at the backside that i can't see. Anyone else have to deal with this bastard of a coolant line?

Mrmerlin

those dont look like coolant lines rather they are for vapor control.

did you install a new coolant cap?
is the coolant tank turning tan or brown, or have any cracks
does the tank collar have white crusty deposits around it?.

maybe the coolant is leaking from the overflow and dripping onto thoise hoses,
NOTE the level of the tank should be just above the seam

safulop

You need a shop to pressure-test the system so they can watch and see where the coolant is coming out. You could be chasing wild geese until the cows come home.

MainePorsche

Unless you can visualize with surety where the leak is with the engine running and the heater on, I would have to agree with safulop.

Bonton

Hmmm, the tank is turning brownish/ perhaps a new cap will work. but no obvious-sqirting leak that you might expect.

MainePorsche

Engine running, airbox off, heater on, mirror and light in hand, and find/visualize the leak.

safulop

I don't work on my own car much but I know this: with a 928 you need a good diagnosis before beginning a treatment plan.

FredR

No sure which hoses you are talking about but cutting into and partial replacement thereof is not a sound way to go if you are talking about any hose or specifically the hoses too and from the heater core- either they are good or they are not. If not replace assuming they are the root cause of the problem.

The other often overlooked possibility for mysterious dissappearance of coolant is the tranny oil cooler in the passenger side end tank. The ATF cricuit operates at little more than paddle around pressure so a leak there can take coolant into the ATF- not a good thing if this happens.

It sounds as though you have a leak into the engine bay so that is a relatively good thing- just have to find our where it is leaking from. First thing I look for are those inspection caps and more specifically tension of the bolt holding them in place- what a crock of a design.

Regards

Fred

Bonton

Can anyone post a picture/diagram of the cooling system? I can't see the "y" hose that leaves the expansion tank, also is there an expansion valve in the same vicinity?