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Discussion Starter · #1 · (Edited)
Hi guys.

Haven't been on the board for a while, just moved into a new house (with a garage!)

Anyway...

1989 16v N/A Auto

Background: Changed head gasket and radiator about 400 miles ago - car hasn't been on the road much since then as I changed the timing chain two weeks ago too...

Coolant was still full of oil so today I decided to try and flush the system to determine whether the HG change was good and to remove the crap.

Removed the radiator drain plug, chucked a load of water into the header tank. Also removed and flushed the heater core (removed the top hose and bottom hose and flushed water through the top hose).

Removed the header tank and washed it out - still brown but it's just discoloured.

Put it all back together, added water and antifreeze and bled the system with the top bleed nipple on the thermostat.

Coolant was ok until I squeezed the large bottom radiator hose that feeds the transmission cooler ('in hose' type), then it filled up with mayonnaise again.

Does this indicate that the transmission cooler is shot? Also, I can't get any significant heat out of the heaters any more - the system is bled as far as I can tell (when I crack off the bleed nipple, water streams out and keeps on coming).

Anyone got any ideas?
 

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Those coolers do leak occasionally.
Sometimes you can see reddish oil droplets in the morning after the oil has had time to separate.
 

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Discussion Starter · #3 ·
Cheers Jim,

I've just spoken to my mechanic, he reckons it's possible but that it should be more obvious than it is - he thinks it's just crap stuck in the system from before the gasket change. I'm going to drain and flush the coolant again in the next few days and see how it goes - I might whip the cooler out and have a look at the same time. This should fix the air bubble in the heater matrix at the same time...
 

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Just carried out a coolant drain on my N/A C900 auto and I notice that you did not mention draining the engine block…?…did you?

If you did not then that might account for the mayonaise since the engine block holds 4L and also there is ~1.5L held in the lower radiator output (to water pump via trans. oil cooler) hose (this is because the auto oil cooler into which this hose runs into is positioned below the rad. drain plug)

just re-read your post and see that you changed the head gasket so I suppose you did drain the engine block…but unless you took off that bottom hose from trans oil cooler the there would have been old bad coolant hanging in there.
Also, how does your trans. oil look like?…if trans oil is getting into coolant then might expect coolant to get into it.
 

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Discussion Starter · #5 ·
finbarr said:
Just carried out a coolant drain on my N/A C900 auto and I notice that you did not mention draining the engine block…?…did you?

If you did not then that might account for the mayonaise since the engine block holds 4L and also there is ~1.5L held in the lower radiator output (to water pump via trans. oil cooler) hose (this is because the auto oil cooler into which this hose runs into is positioned below the rad. drain plug)

just re-read your post and see that you changed the head gasket so I suppose you did drain the engine block…but unless you took off that bottom hose from trans oil cooler the there would have been old bad coolant hanging in there.
Also, how does your trans. oil look like?…if trans oil is getting into coolant then might expect coolant to get into it.
Thanks for the reply.

I didn't drain the block as I couldn't get to it, although all the fluids were drained out as the engine was pressure washed and left for a week when I changed the chain.

Thanks for the tips though, I will have another go soon.

Currently fighting with my other Saab, the battery has inexplicably gone flat overnight, and I can't get it jumped with another car, so the battery has just been removed to be charged...
 

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The engine drain plug is difficult to get to and undo on an N/A C900 but I managed too so if I can…… :eek: . I will post pics of the tools etc in the near future but if you would like to know before that do pm me.

Also,

1. Just wondering but when I did all this I noticed that the heater core does not fully drain does it?…the bottom hose is not at the lowest point I suspect since when I flushed it out on its own a significant amount of old coolant came out. What do you think?

2. When I refilled the coolant system it only took 5.75l ( :confused: ) to fill it to mid point min/max, so if there is other (presumably clear "flushing" water) left in the system somewhere then one would surely need to take this into account with how much anti-freeze is added.
 

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Both the radiator and heater core can get blocked in places by gunge but will still allow water to flow. You then seem to have a working coolant system but it is actually well below par. Pouring water through a system will not flush effectively as water will take the path of least resistance. It is worth getting a radiator flush fluid from somewhere like Halfords and following the instructions, you'll have a better chance of restoring the system.
 

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finbarr said:
The engine drain plug is difficult to get to and undo on an N/A C900 but I managed too so if I can…… :eek: .
Yeah, getting to it is the easy part. The hard part is undoing it without the aluminium mount falling to pieces. But that's not such a big deal either as a new one is cheap -- even here at the end of the world!
 

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The heater core will pretty much not flush at all. There's very little flow through the core even with the heater valve fully open. The heater valve is a constant flow design so that, when it is fully closed, coolant still flows at full tilt through it inlet and outlet pipes. The only way to flush the heater core is to take it out of the car and work directly on it.
 

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cdaly said:
The heater core will pretty much not flush at all. There's very little flow through the core even with the heater valve fully open.
Could it be the valve?

The only way to flush the heater core is to take it out of the car and work directly on it.
If you're going to that hassle, is it worth just lobbing it and putting a new matrix in? I dunno about c900s, but plenty of other cars have problems with them leaking or bursting in old age, let alone the silting up.

I know the radweld fairy's been at mine in the past, and the heater's nowhere near as effective as I remember 'em being - but "it'll do".
 

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It's part of the valve design. There's an in pipe to the valve which flows directly to the out pipe. Within the valve there's a small hole (max 10mm square) which is opened / closed by a slider shutter which is controlled by the heater knob. This is the only route for coolant into the matrix and so there cannot be that much flow into the matrix.
 

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cdaly said:
It's part of the valve design. There's an in pipe to the valve which flows directly to the out pipe. Within the valve there's a small hole (max 10mm square) which is opened / closed by a slider shutter which is controlled by the heater knob. This is the only route for coolant into the matrix and so there cannot be that much flow into the matrix.
Gotcha. I was thinking in terms of matrix being blocked.
 
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