986 S coolant issue.

[srsmith73]

I've got a 2004 Boxster S and noticed something odd about the coolant.

My car had been sat for about 3 days on drive and when I came to move it I noticed that there was a coolant leak underneath, roughly in the middle of the car basically underneath the drivers seat. I looked in the coolant tank in the boot and noticed it was quite low, so I topped it up. I took it out for a drive today, about 15 miles and the temp stayed at just over 80. I’ve put a new cap on the expansion tank I got from a local Porsche dealer. Looked again today and the coolant had dropped really low so topped it up, took for a drive to get to running temp and then drove it hard for quite a while and temp gauge never budged. Looks like it only leaks when the engine has cooled down over night.

Anybody any idea what could cause this?

[mark2604]

Almost certainly one of the crossover coolant pipes situated in front of the peddle box under both sides of the car. They are a mixture of plastic tubes and rubber hose with steel connectors which corrode and leak. Quite a phage to get to. Or it could be a radiator but the leak would be further forward if it was

[kev b]

The whole cooling system will probably be pretty tired by now, might be wise to give it a proper overhaul.

The radiators in particular if not cleaned regularly trap damp dirt and leaves which rot away the metal unseen until it’s too late.

A vacuum bleeder makes refilling simple if you can borrow one, needs a compressor though.

Make sure you have enough buckets to catch all the coolant!

[srsmith73]

Cheers guys for the heads up on what it could be. I’ve booked it in at a local Porsche indie and they’re going to take a look at the leak whilst they’re doing the service.

[jakesmith]

Sure it wasn't condensation from air con? That can drip under the car

[edc]

mark2604 said:

Almost certainly one of the crossover coolant pipes situated in front of the peddle box under both sides of the car. They isare a mixture of plastic tubes and rubber hose with steel connectors which corrode and leak. Quite a phage to get to. Or it could be a radiator but the leak would be further forward if it was

The cross over pipes seem to be a 987 rather than 986 issue.

[Semmelweiss]

My wife's 986S had the same. Low coolant light came on, topped up with 5 litres! Test drive and noticed leaks from middle of the car.

Water pump replacement. They normally start with slow leaks, and then catastrophic failure.

If the reservoir is not split, then this is the likely issue.

https://youtu.be/ZN4pBnGynIA

[mark2604]

edc said:

mark2604 said:

Almost certainly one of the crossover coolant pipes situated in front of the peddle box under both sides of the car. They isare a mixture of plastic tubes and rubber hose with steel connectors which corrode and leak. Quite a phage to get to. Or it could be a radiator but the leak would be further forward if it was

The cross over pipes seem to be a 987 rather than 986 issue.

Yes you are right, I had a 986 and a 987 at the same time and it was the 987 we had to change, but nonetheless if the leak is from that area it must be a strong contender for the fault.
Would be good to hear from OP once the diagnosis is confirmed

[srsmith73]

Checked yesterday morning and there was no leak and the coolant had only dropped slightly which I presume is just down the reduction in fluid temp. Went for a drive and no leak.

Also how dangerous is it to keep topping it up with water rather than coolant?

[Semmelweiss]

Coolant has a lubricant in it which will keep your water pump bearing going for longer, as well as protection at lower and higher temperatures.

It's £12 for 5 litres at Eurocarparts

[srsmith73]

Semmelweiss said:

Coolant has a lubricant in it which will keep your water pump bearing going for longer, as well as protection at lower and higher temperatures.

It's £12 for 5 litres at Eurocarparts

Cheers. What’s the best coolant to get?

[Semmelweiss]

Triple QX Ready mixed. Whatever colour is in your car, they are all the same.

[ooid]

srsmith73 said:

I took it out for a drive today, about 15 miles and the temp stayed at just over 80.

I think later 986 cars temp gauge never moves beyond 80, unlike first gen1. I had the 2000 2.7, and the temp gauge was quite sensitive.

My suggestion would be the put the car on a ramp (local garage?), start running and see while on idle. If there is any leak from the pipes, radiators or whatever, it would be visible. If there is no visble leak, but you are losing coolant ,that's bad news than = intermix (it might be in the oil)

Have you checked your oil?

[edc]

I don't think there's any difference in the temp guages. Have had a 2000 and 2004 and notice no difference.

[srsmith73]

I’ve checked the oil cap and the dipstick and there’s no mayonnaise and they both look very clean. Plus in don’t get any white smoke on startup or whilst driving.

[edc]

The coolant has obviously leaked escaped from somewhere. When you filled it up, there was probably some air in it. It probably got in from the same place the coolant came out and was drawn in as the system cooled. When you drove again it had the effect of part bleeding the system and pushed the air to the highest point hence you see low coolant level.

The likelihood is the original cause it still there but only happens above a certain temp or pressure. I would raise the rear of the car, open the bleed valve and cap, let the engine warm up and top up as needed. Put the cap back on leave the bleed valve open and blip the throttle a few times then hold it steady at circa 3k rpm for a few seconds. Top up as needed.

[srsmith73]

And the prize for guessing what the problem was goes to [drum role please]......@mark2604 it was indeed a cracked pipe. Garage replaced the pipe for £90, happy days. Problem is I’m on holiday and the garage is dropping the car back to the house and I can’t play with it until I get back.