Engine Block Coolant Drain Plugs

[aerosilver]

Hi all,

I have just done a coolant flush. I flushed the radiator, and then removed the N/S engine block plug as it was the easiest to access. The coolant ran out clean, no crud. I then attached the hose to a length of plastic tube that I fed through into block plug hole and gave it a good high pressure blast until you could drink what came back out. Because I did this I didn't bother with the O/S block plug, as I assume they both lead into common waterways and I'm assuming the pressure of water I managed to get into the N/S one will have cleaned them all out sufficiently. Is this assumption correct?

Cheers,

Bob
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[Duncan Skye]

Hi Bob,

Common waterways will indeed allow the flushing of water, but bear in mind that it is a fluid. Crud at the bottom of a waterway will be sedimentary in nature and will probably not be affected by an exchange of water, because that is what the water pump does in any case. If there is sediment there, you'd need a turbulent or fast flow to get sediment into suspension and that kind of flow may not be present if water is coming from the other side of the block. Note that after removing the bottom hose, each plug holds back its own head of water, which empties out on removal of the plug.

My car had sat for at least four years before I took the tarpaulin off. Even though anti-freeze and coolant were present, one plug ran free, but the other was sedimented up and needed a poke with wire and a good strong flush. I did that as a short block on a rotating stand and eventually I was satisfied I could do no more.

I'd suggest if you don't know what's behind that plug, you might try and get it out. Just to set your mind at peace..

With best wishes,
Duncan, Skye

[Moraystag]

Bob I agree with Duncan take out both plugs to get rid of any crud. Also you'll need new fibre washers for the plugs I suspect

Mike

[aerosilver]

OK thanks guys. I'll definitely remove both plugs next time, but it's all back together and burbling in the sunshine now! I'm not too worried at only having removed one this time round as so little muck came out, and there was hardly any in the radiator either. In addition I gave the the whole block a good flush through when I had the heads off 2 years ago.

Cheers,

Bob
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[Duncan Skye]

OK thanks guys. I'll definitely remove both plugs next time, but it's all back together and burbling in the sunshine now! I'm not too worried at only having removed one this time round as so little muck came out, and there was hardly any in the radiator either. In addition I gave the the whole block a good flush through when I had the heads off 2 years ago.

Cheers,

Bob
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Fair enough Bob, It's only you who can have the 'feel' for your own car. If you've kept the anti-freeze levels up in the interim, you should be OK.

Happy motoring,
Duncan

[Rich437]

I am in the process of changing the viscous coupler and decided to do a full flush of the cooling system as I had the radiater out. Having read the several threads on the forum (thnks for them all) I have taken the drain plugs out of the block. The O/S drain took a quick prod and is flowing freely, but the N/S one ( the most difficult to reach of course) will not flow. I have used a screw driver, a piece of coat hanger, and even a twist drill (by hand), but nothing. I do get some crud which is wet, but no flow. Is there something else I can do, or are my suspicions that there is a blockage in the system correct? When I filled the system, I connected a hose to the heater inlet pipe, and held my hand over the radiater inlet hose to obtain a pressure. ( I have taken the heater out of circuit as it does not work and I did not want to have an air lock. This I did by connecting the heater inlet pipe to the the inlet on the near N/S block)

Thanks

Mike

[Mij]

Sorry, the previous note was me. I entered the forum with the guest user name by mistake. My first time!
Mike

[Moraystag]

Mike just keep prodding away as you will have to get maxumum free flowing or problems will follow for sure

Mike

[Duncan Skye]

I am in the process of changing the viscous coupler and decided to do a full flush of the cooling system as I had the radiater out. Having read the several threads on the forum (thnks for them all) I have taken the drain plugs out of the block. The O/S drain took a quick prod and is flowing freely, but the N/S one ( the most difficult to reach of course) will not flow. I have used a screw driver, a piece of coat hanger, and even a twist drill (by hand), but nothing. I do get some crud which is wet, but no flow. Is there something else I can do, or are my suspicions that there is a blockage in the system correct? When I filled the system, I connected a hose to the heater inlet pipe, and held my hand over the radiater inlet hose to obtain a pressure. ( I have taken the heater out of circuit as it does not work and I did not want to have an air lock. This I did by connecting the heater inlet pipe to the the inlet on the near N/S block)

Thanks

Mike

Hi Mike,

What you've likely got is crud lying in the bottom of the water jacket that is served by that drain plug. It's been there for long enough for 'concretion' to begin to set in and I think the only way to get the blockage clear is to persist with the poking, prodding and twisting until you break through. You'll (hopefully) find that it's not a deep layer, just tough because it's awkward to get to. Once you do break through, have a poke around with a piece of wire with a small bend on it, then flush again to get what crud you can out of it. Mind your eyes when you do break through, as there will be a reservoir of liquid and sediment behind it.

Next time the heads are off, you can get a long screwdriver or stiff piece of wire down the cooling slots and work the sediment free.

I hope that helps,
Duncan, Skye

[Mij]

Duncan/Mike,
Thanks for that. How for should you be able to push a screwdriver into the hole? I have used a piece of copper wire and gone in about 2cm, then it seems to hit the other side of the cavity, or is this the concreted crud?

Mike

PS. Tried again and got through the crud!!!! The answer to my question is about 3.5 cm. Now all I have to do is build it all up!

Thanks to all again

Mike

[Duncan Skye]

Duncan/Mike,
Thanks for that. How for should you be able to push a screwdriver into the hole? I have used a piece of copper wire and gone in about 2cm, then it seems to hit the other side of the cavity, or is this the concreted crud?

Mike

PS. Tried again and got through the crud!!!! The answer to my question is about 3.5 cm. Now all I have to do is build it all up!

Thanks to all again

Mike

I've just stuck a probe into the (left hand) drain plug and it went in 3.2 cm before hitting the opposite casting wall. (I can only access the left hand drain port because of where the spare engine is stashed). On thing I did notice though, is that the drain plug thread is almost 1cm long and there is about 2mm beyond that in the block before the tapped casting turned into a blind end. That has been drilled through to reach the water jacket but only with something like a 4mm drill. So there is a possibility that you were butting up on the land either side of the 4mm hole, rather than pushing through crud. Eventually you did push through, and it is possible that the only crud in there was simply that which had settled in the drilling.

At least you have a result, and you could investigate further when you take your heads off.

Incidentally, copper wire isn't bery strong for poking and gouging. I use 'normal' fencing wire in preference, which is high tensile and very robust.

With best wishes,
Duncan

[wader3]

I have a stripped block at the moment and was doing this myself yesterday. Even a power washer nozzle pressed right into the drain plug did nothing. With a torch and small electrical screwdriver I was able to clear it. For some reason there is a semicircle at the back of the hole that is part of the cast, so as you suspected, prodding will only have effect in one place!

Rob

[nib]

Just a thought but I wonder if some K-seal finds it way to these holes?
Mark

[stag8manod]

Hi all, To make a suggestion. Next time you have the heads off to improve access, make/install remote drains and a flush can be done at any time. I have fitted them to my engine but as it is still in pieces I haven't as yet been able to try them out.
Cheers Ian A

[Duncan Skye]

Hi all, To make a suggestion. Next time you have the heads off to improve access, make/install remote drains and a flush can be done at any time. I have fitted them to my engine but as it is still in pieces I haven't as yet been able to try them out.
Cheers Ian A

Yes, these drain plugs can be a right pain to get at once installed and a remote tap could be a real time (and knuckle) saver.

Do you have a piccy of what you've done so far, or any details of what parts you used (supplier) etc?

With best wishes,
Duncan, Skye.