SP250 engine cooling jacket blocked

[Jez]

Gents,

I've undone the left side drain plug on the engine and found no coolant flows out (the right side is fine). Poking around with a piece of stiff wire brings out some damp, black grainy sludge (casting sand??) but nothing more and blowing with the airline didn't do much either. Are there any creative options, or is it necessary to remove the core plugs or cylinder head? The upper core plug looks just about accessible, but the lower one is hidden behind the exhaust manifold, which looks to be a right pain to remove whilst in the car.

Cheers - Jez

[Ian Slade]

In cases like that I have always filled up with neat anti freeze and run about for a couple of hundred miles, then tried again

[Christopher Storey]

The best substance for clearing this sort of sludge from a cooling system is citric acid. This can be bought in powder form from many pharmacies . The packet should be mixed with water thoroughly, and then added to the cooling system and the engine run to full running temperature daily for about 3 days . The solution should go green, and after flushing , preferably with a hose or even a pressure washer, most if not all of the crud should be gone

[Jez]

Thanks for the suggestions. I've heard of using Citric acid for this kind of thing, and I can see how that would chemically affect rust, scale etc, but will it or Ian's 100% antifreeze affect this kind of sand based sludge? I tried a proprietary flush (not for as long as suggested here though) which didn't seem to have pulled out much when I drained it off.

Cheers - Jez

[Christopher Storey]

I really don't think that 100% ethylene glycol would have the desired effect, because it contains ingibitors to prevent it causing surface erosion to the aluminium parts of the cooling system , and it is a very expensive way of going about things . Citric acid, on the other hand , will cost you about £3

[Fossil]

Christopher

Do you think it would be worthwhile using citric acid in an older engine from time to time, say every ten years, to keep the block waterways in clean condition? Are there any potential drawbacks to such a proposal?

It is now 20 years since I replaced the core plugs and cleared out the Century block , and the temperature gauge still keeps very steady in summer motoring, but for how much longer I wonder sometimes?

Regards

Geoff

[Ian Slade]

Providing the block has been thoroughly flushed after build or a long lay up dry using a higher than normal anti freeze mix the engine will stay clean if drained annually. I had a boat with a Ford Kent block indirectly cooled, I couldn't drain the block due to crud, filled it with pure anti freeze and left the plug out, fired up the engine and ran it until the crud started to ooze out, kept topping up and collecting the anti-freeze and filtering it until it ran clear. Changed the anti-freeze every year and by year 5 the anti-freeze never changed colour and when drained at the plugs completely clear. The car is worth thousands and the engine rebuild by a trade re-builder is about £5K so what's a few quid on anti- freeze?

[Christopher Storey]

Geoff ( and Ian ) : you could do a regular flush out with citric acid, but I would not think it should be necessary unless there are overheating symptoms. Whether there are drawbacks is hard to say - obviously for it to work at all there is a reaction between the cooling system materials and the acid, but provided it is not left in for too long I doubt that it would cause much harm. I am interested in Ian's idea, but I wonder whether he was in fact using modern Organic Acid technology antifreeze which might well have the effect he describes, but is said to attack older systems if left in permanently , particularly where there is brass in them

[Bud]

When the engine is back and running get hold of one of those inexpensive hand held IR thermometers and look around the engine for HOT SPOTS. That will tell you if you have cleared all the casting sand from the water passages.
Once free flowing and all the casting residue eliminated the passages should never clog up with material unless there is gasket failure or cracks to allow electrolysis or oxidation etc. or leaks and corrosion.
Make sure to get the fluids to flow into and out from the block at all openings freely.
There is advertised a plastic handy home drain snake ( a couple feet long, flexible, and with barbs on the tip that catches obstructions with reverse teeth ) that may be useful as it would readily go around passages a wire or probe may not.

[Fossil]

Thanks Christopher, I'll just leave things alone on the "If it ain't broke" principle.

Cheers

Geoff