| Author |  Topic  | |
EdinburghJoe
V4 Fan
United Kingdom
162 Posts |  Posted - 15 May 2018 : 15:02:32  
| Hi all,
I’ve got a bit of an overheating problem on my 1973 96. Nothing serious, but the temperature nudges up beyond Normal – the hottest it has ever been is around half way to the start of the red (this with the cabin heater on too!). When it gets hot it also tends to force coolant out through the expansion tank cap. The weather’s been about 20C tops – warm, but not exactly extreme.
I gather that there are loads of potential causes for this, but I thought I’d start with the obvious one and flush the cooling system. I’ve got some radiator flush, but after using this I think reverse flushing the system with fresh water sounds like a good idea.
Haynes says how to do that for the radiator (disconnect and flush water in from the bottom), but what about reverse flushing the engine? Someone suggested disconnecting the lower heater pipe and flushing it from there. Does this sound right? Any other suggestions?
Is this a good idea – I can see how it might loosen blockages, but can doing this cause damage or make things worse?
Thanks,
Joe
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Woody
V4 Guru
United Kingdom
2764 Posts | Posted - 15 May 2018 : 21:18:30
| Drain the radiator, opening the bleed screw at the heater housing and catch the water in a bucket so you can check what is coming out. I would recommend removal of the block drain plugs both sides, at least near side above the starter. Use a HEX socket 11mm. Multi-point Socket will take out the corners. Hopefully they will come out clean. Once drained look into water jackets to check for crud and flush out. Back in the 70's would use a radiator flush solution such as Wynns. Check also water pump. Is there any trace of leaking from the bearing/inner seal.
Worth removing radiator and tipping it upside down and flushing via the bottom. Refill with a good mix of anti-freeze. Water only encourages rust.
Ensure the system is bled well.
When the engine is running is the thermostat opening/closing apparent?
When all is done, it would be worth checking that the engine is running efficiently using a Gunsons Tune kit. Not too expensive and worth the effort. |  |
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Derek
V4 Guru
United Kingdom
2191 Posts | Posted - 16 May 2018 : 12:01:16
| | Make sure that the top of the expansion bottle isn't distorted. If it is, the cap is cocked up one side a bit and gives a bad seal. The tabs on the cap also don't fit correctly. Had that problem and it would boil over after a fast run. Used to often boil over in the queue after arriving at a car show. Was using a new cap but it took a while to notice the problem with the bottle. | |
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EdinburghJoe
V4 Fan
United Kingdom
162 Posts | Posted - 16 May 2018 : 17:46:28
| Thanks for the replies.
Woody, a couple of things:
- when you say 'look into water jackets' do you just mean through the drain plug holes? If I see any crud there I can poke at it with a piece of wire to free it up?
- Do you mean use a colortune for mixture, or a strobe for timing? I have both...
Derek - I think the bottle and cap seem OK but I'll check. If it is OK, and the coolant continues to boil when the temperature is only a bit over Normal then should I use an extra washer to produce a firmer seal? I don't want to make the seal TOO good or I guess this could lead to something bursting somewhere!
Joe | |
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melle
V4 Guru
United Kingdom
3833 Posts | Posted - 16 May 2018 : 21:40:36
| If the expansion bottle cap works properly (have it pressure tested) the safety valve will open if needed, so no worries about sealing it too well. Same for the rad cap, make sure it seals and pop a thin rubber washer under it if it doesn't. Do not overfill the system, expansion bottle level up to MIN is OK. Also make sure the cap with the valve is on the bottle and the "solid" cap is on the rad.
Before flushing the cooling system I would check compression and ignition timing.
www.saabv4.com | |
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Woody
V4 Guru
United Kingdom
2764 Posts | Posted - 16 May 2018 : 21:50:27
| Poke ..yes
and as you have both, use both.
When I last used the Troll the temp gauge when at running temperature was to the right of normal. This was tested with a centigrade gauge which equated to 95 degrees. I have the rally header and larger radiator and it still gets hot with a tuned engine. I am tempted to put the standard engine back into see if it will run smoothly on this unleaded fuel we have to put up with these days. Additive helps too. | |
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Derek
V4 Guru
United Kingdom
2191 Posts | Posted - 17 May 2018 : 11:41:08
| | If the bottle is good and the cap is also good it should all work properly. I think the standard cap is 7psi but I'd happily use a 10psi one. | |
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EdinburghJoe
V4 Fan
United Kingdom
162 Posts | Posted - 17 May 2018 : 12:37:51
| I forgot to mention that my engine has cylinder heads with larger than usual valves. I don't know any more detail than that (the previous owner put them in). Is this likely to create more heat and make cooling always a struggle on the standard system?
I'll do the flush tomorrow as per Woody's reply (including removing the radiator). I have already flushed it twice over the past couple of years, but I've never removed the radiator, and the coolant looks fairly brownish at the moment. I'll also check the tune with my strobe and then see how it goes before delving further...
Joe | |
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OWEN
V4 Fanatic
United Kingdom
318 Posts | Posted - 22 May 2018 : 22:59:28
| | You don't say when the overheating happens; fast driving, normal driving or idling? (or all 3!) | |
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72sonett3
V4 Fanatic
Spain
269 Posts | Posted - 24 May 2018 : 16:59:45
| quote:
Originally posted by EdinburghJoe
... my engine has cylinder heads with larger than usual valves.
My Sonett has those too (V6 valves), an electric fan (and flat distribution cover) and it does not overheat at all.
In stop&go traffic or long idle the temp will go up bt then I switch the fan on with a manual switch and then the temp goes down again.
Do not try to cure the symptoms but do what Melle suggests; check compression and make sure the timing is OK.
--
'72 97
'77 96L conv.
'79 96GL (LPG)
'83 900i (LPG)
'95 900SE conv.
'99 9-3T |
Edited by - 72sonett3 on 29 May 2018 15:15:24 | |
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EdinburghJoe
V4 Fan
United Kingdom
162 Posts | Posted - 29 May 2018 : 12:40:20
| Hi all,
Sorry for the delay getting back, but I wanted to take time to get some useful info.
I've drained the system as per Woody's method, including using Wynns, and removing and reverse flushing the radiator. Brown water came out of the engine block, some sludge out of the radiator (plus the pipe to the expansion vessel was blocked with it), so I flushed everything out several times until the water came out clear.
Thought I’d be clever and spray the removed radiator with a water jet (mains pressure) to clear out the grill. Not a great idea – the metal fins were so corroded I blasted some of them clean away, and bent some of the others. From what I’ve read on this forum, I was expecting the radiator to have two definite horizontal pipes, with vertical fins between them. Mine had no obvious pipes, but thin flat horizontal bars (which I presume carry the water) with very thin ‘W’ profile metal fins between them. Is this a ‘normal’ radiator, and will it be easy enough to get it repaired eventually (I guess at the very least it needs the metal fins replacing)?
Anyway, I got the radiator back on as it was, took the car for a drive (about 20 miles – bit of traffic, bit of motorway with a long uphill, bit of country roads) and it was pretty much as before. Certainly no worse – a bit above ‘N’ when I stopped.
Then I tried the timing strobe – the index was off the scale at idle, probably about 20 degrees BTDC, so I adjusted it back to the required 6. This made the idle worse, so it needed a bit more on the throttle stop, plus unscrew the volume control a turn or two to get it idling properly (I have a FoMoCo).
Went for another drive yesterday and it seemed a bit better. Crept slightly above ‘N’ on the hill, otherwise all good (though to be fair it was a slightly cooler day). It might even have been running quieter (though I could be deluding myself!)
Would the timing being so far out likely have been contributing the overheating?
I think I’ll leave things as they are as it’s working OK, but I’ll need to fix the radiator ‘one day’ as I’m sure this isn’t helping. Does anyone have any suggestions what the best thing to do would be for this?
I've not tested the compression as I don't (yet) have a compression tester...
Thanks again,
Joe
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72sonett3
V4 Fanatic
Spain
269 Posts | Posted - 29 May 2018 : 15:24:24
| quote:
Would the timing being so far out likely have been contributing the overheating?
Yes, on my 1977 96 (with solex 32TDID) I once had the vacuum hoses connected the wrong way and it would overheat as the timing was off. after I corrected it, it was OK.
quote:
... fix the radiator... any suggestions what the best thing to do would be for this?
Replace it with a new one.
--
'72 97
'77 96L conv.
'79 96GL (LPG)
'83 900i (LPG)
'95 900SE conv.
'99 9-3T | |
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green96v4
V4 Mad
Canada
738 Posts | Posted - 30 May 2018 : 11:50:13
| quote:
Originally posted by EdinburghJoe
Crept slightly above ‘N’ on the hill, otherwise all good (though to be fair it was a slightly cooler day).
FWIW my temp gauge needle has always sat just to the right of the N - when it was my daily driver 20+ years ago and after the rebuild (where I've replaced every serviceable component, also had my rad re-cored) I'm 99% certain I would have replaced the thermostat, not sure if there are different temperature specs for them.... | |
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| | Topic | |
Overheating and Reverse Flushing
