(Home) Losing water

i have recently had my head replaced and my radiator re-cored but i am still topping up my coolant by about a pint every 3 days.I cannot see any leaks anywhere and it was pressure tested at the garage that done the work.Why is this ,can any body help?

- (#11321) dave oreilly, 4 Jun 04 13:36

there have been some cases where leaks will only develop when the engine is hot. the most likely place will be under the drivers seat, because there are a lot of coolant pipes that can leak at the joints. if you havent already done so, replace the radiator cap with the latest toyota float type part number 16401-64501.
- (#11321) dave Bright (Bournemouth), 5 Jun 04 04:19

I have had a leak develop since I renewed the coolant a couple of months ago. I first noticed the expansion tank level dropping faster than usual. Now I see a puddle under the car and sometimes, when cold, about one drip every 5 seconds from the front left (passenger side) of the sump.

Does anyone know if you can get the top plastic cambelt cover off without removing the drivers floor? and then can you see enough of the water pump pulley/shaft to see if cooolant is coming out there?
- (#11321) Dave Mason (Sussex), 7 Jun 04 02:38

Yes you can, and yes, you can. But I'd check the thermostat housing first...

- (#11321) David Miller, 7 Jun 04 03:30

Thanks David. Yes the thermostat housing seal fits the symptoms best but I thought watching the water pump might have been an easier check to do first.

What would I be likely to find on the thermostat housing seal? O-ring hardened? split? shrunk? Might it be that just tightening the two bolts is a first step?

- (#11321) Dave Mason (Sussex), 7 Jun 04 04:05

I swap my thermostats regularly and use the same O rings which are very hard wearing. I don't think you will find they go hard but will flatten over time. A common problem is with an ill-fitting O ring where it is possible to damage it. Easily done as it is so hard to see what's going on when fitting the housing to the block.

I'd be inclined to remove the housing and check the condition of the O ring and check that the housing face is clean and flat. If in doubt renew the O ring as they are only about a couple of quid.

- (#11321) Ian Dunse (Derbs), 7 Jun 04 04:57

im losing about half a pint every 50 miles.Took off radiator cap and watched the water constantely bubble.head gasket ,radiator just replaced,apparantely!!Owner for 1 week only,please help

- (#11321) Robin lloyd, 9 Jun 04 12:14

If work has just been done and the system was not refilled really slowly then the cause MAY just be trapped airpockets in the system.
Can you say if the apparent coolant loss is via the expansion tank? In other words do you find the expansion tank full or empty? and is the system full under the "rad" cap when cold? If you find the tank empty then it may not really be loss, just being sucked back into the system to replace expelled air. If you find the tank full and system not brim full when cold then the suck-back may not be working, air leaking in via radcap or pipe to exp. tank.

- (#11321) Dave Mason (Sussex), 10 Jun 04 05:15

As you said david I have seen system low and tank full but last time both were low.No water in oil.Drives okay.

- (#11321) Robin lloyd.(Pembs), 10 Jun 04 06:35

This could be a low pressure problem, or a faulty draw back mechanism. If you havent yet, replace the radiator cap and check the pipes that from the filler to, and inside the expansion tank. Gently twist each pipe end, on the fittings, and see it it turns. If it does then its not sealing properly. Just reposition the clip for a temporary fix.Have you had a hot presure test done yet?

- (#11321) dave Bright (Bournemouth), 10 Jun 04 06:47

Two weeks and a replacement water pump later, my coolant leak seems to be fixed. That pump/injection-pump-bracket assembly is quite something. I can see why it's worth changing it when you're doing a cambelt.

I noticed a vertical tunnel in the casting under the pump shaft, as if to ensure that coolant leaking via the seal/gland goes down there rather than on to the pulley and belts - so no way you would see that sort of leak by peering into the cambelt enclosure. However there was no trace of leaking having occured there anyway, in fact the whole pump assembly seemed in fine condition.

The mechanic who changed the pump for me commented that the gasket was in bad condition - took a lot of cleaning off the block - so, since nothing else was changed, we think that was where the leak occurred, brought on by the dissolving and leak-finding power of the fresh coolant (deionised water 2:1 antifreeze).
- (#11321) Dave Mason (Sussex), 22 Jun 04 03:05