Possible solution for blocked crankcase Drain Tap

[JeffR]

Earlier this week I decided to flush the cooling system of my TR4 before refilling with new coolant ready for the new season.

I drained the rad and refilled with a solution of Prestone radiator and engine coolant flush and then ran the car on idle for an hour before draining it.

Before starting, I already knew that the outlet at the bottom of the block where the drain tap is was blocked with sediment and had been for several years with all previous attempts to clear it having failed.

Again this time, after having spent an hour or so trying to clear it with various tools and bent wire etc - and all having failed, I hit on the idea of trying a well known kitchen and bathroom limescale remover just to see if that might work.

I gave a good spraying to the inside of the blocked area, agitated it with a thin screwdriver for about 10 mins and then left it for an hour.

On returning and after a little more agitation with a bent wire during which a lot of softened debris came out - there was a sudden rush of coolant as water spurted out in full flow. Hooray!

I'm probably the last person to have thought of this idea - but if it is of any help to anyone else it's worth a try.

JeffR

[BlueTR3A-5EKT]

Well done.   The good poking with a thin screw driver probably made it realise it needed to let go.

Hope you covered the starter motor with a plastic bag to keep any water out of the workings and electrics.

[JeffR]

Yes, indeed Peter.

None of the poking has ever worked before? Don't read too much into this.

Cheers,

JefR

[Lebro]

Did you poke through the tap, or after tap was removed. You can get much further in the 2nd way.

Bob

[JeffR]

Hi Bob,

My 4 doesn't actually have a tap, instead it has a threaded plug as many late TR4s do. So, yes, I removed the plug first.

Regards.

JEFF

[Nigel C]

Does anyone know if there's a way to fit a tap (I have a plug) that could have a pipe fitted so when draining it doesn't go through the start motor as getting a bag on is a fighter for me.

[james christie]

First find a tap that doesn’t leak! 

james

[Lebro]

I have the same style of (original) tap on the block & the Red, neither leak.

Bob

[ianc]

Dismantle the tap and, using fine grinding paste, lap the swivelling part into the outer casting - I must thank Carl at Revington for demonstrating this simple fix to me many moons ago.

Ian Cornish

[BlueTR3A-5EKT]

17 hours ago, Lebro said:

I have the same style of (original) tap on the block & the Red, neither leak.

Bob

Nor does my stainless steel plug/bolt

[John Mellor]

My tap won't  turn and it doesn't leak, so its  good news and bad news. However the tap is jammed in the block and I was afraid to use force lest I end up with a leak and a broken tap stuck in the thread. Chickened out and just flush coolant via rad plug. Anyone got thoughts on this

Regards  John M

[Motorsport Mickey]

I hate having a potential large leak or breakdown saved up for away from home.

So on the basis a "buggers job" is better done in your drive, drop the fluid and warm the tap up with a blow torch (don't melt) and quickly try to TIGHTEN the tap body up or get some movement by using two large spanners at 180 deg to each other pulling and pushing together to keep the force equal on the large nut sized body of the tap. If it moves even a few mm it will probably break the seal  (if it's the BSP tap body it should be, there's only 1 thread and a half on the body that seals it, so should come out). If it comes out cleanly you may be able to strip it down and after cleaning lap the valve in as suggested by Ian (above) and reuse it. If not replace with a bolt or a new tap, but I'd still lap the tap in first before fitting.

Mick Richards

Edited April 7 by Motorsport Mickey

[BlueTR3A-5EKT]

4 hours ago, Motorsport Mickey said:

I hate having a potential large leak or breakdown saved up for away from home.

So on the basis a "buggers job" is better done in your drive, drop the fluid and warm the tap up with a blow torch (don't melt) and quickly try to TIGHTEN the tap body up or get some movement by using two large spanners at 180 deg to each other pulling and pushing together to keep the force equal on the large nut sized body of the tap. If it moves even a few mm it will probably break the seal  (if it's the BSP tap body it should be, there's only 1 thread and a half on the body that seals it, so should come out). If it comes out cleanly you may be able to strip it down and after cleaning lap the valve in as suggested by Ian (above) and reuse it. If not replace with a bolt or a new tap, but I'd still lap the tap in first before fitting.

Mick Richards

The cylinder block thread for the water drain is unf.   I just had to clean out the thread in a block.   Hence my use of a stainless screw to seal instead of the more than unreliable repro drain taps.   I have a spare if you are after one as I had to buy 5.

[Motorsport Mickey]

DOH !...of course it's UNF !, but the rad is BSP which is what I mixed it up with, apologies.

Mick Richards

[phil Dean]

when I took mine out because the actual tap was broken off, it was bunged up with what looked like casting sand I replaced it with a stainless steel bolt and tried to clear the original but it was packed solid. I gave it a really good flush out until the water coming out wash clean but goodness knows what is floating about in the water ways.

 

Phil.

 

[Rod1883]

Peter - how long is/are the 1/2"(?) UNF set screws that you used/sourced? I understand that there isn't very much depth beyond the wall of the block before the cylinder liner is impacted.

[BlueTR3A-5EKT]

1 hour ago, Rod1883 said:

Peter - how long is/are the 1/2"(?) UNF set screws that you used/sourced? I understand that there isn't very much depth beyond the wall of the block before the cylinder liner is impacted.

Will measure the depth tomorrow

Here is the water drain hole thread being cleared.

 

What it was like before cleaning.  The drain hole is visible...just

 

Edited April 8 by BlueTR3A-5EKT

[BlueTR3A-5EKT]

15 hours ago, Rod1883 said:

Peter - how long is/are the 1/2"(?) UNF set screws that you used/sourced? I understand that there isn't very much depth beyond the wall of the block before the cylinder liner is impacted.

The A2 stainless screws I sourced are 1/2" unf 3/4" long thread - and they are too long.  I did think I would put a pile of washers under the screw head but decided that was a bodge too far, as in the future if I forgot to refit the washers I'd be in the effluent.

I have reduced them on the lathe to 7/16" thread length.  Without the sealing washer they screw in by finger force to full depth in my cylinder block, which has had the thread cleaned up.  I use a copper crush washer under the head.

What I bought  https://www.kayfast.co.uk/view-product/UNF-Hexagon-Set-Screws-A2-Stainless-Steel

Edited April 9 by BlueTR3A-5EKT

[Rod1883]

Thanks for the info Peter, glad I asked about the length. Did you say you had a nicely shortened spare........?

Rod

[AJ2014]

A few shots of ‘crud’ build up around No4 liner in my TR4 engine prior to rebuild. I couldn’t believe how much there was and how solid it had become. The drain tap hole was difficult to clear.
Oxtail soup anyone..

Ade

 

Edited April 9 by AJ2014
Add Video

[BlueTR3A-5EKT]

4 hours ago, Rod1883 said:

Thanks for the info Peter, glad I asked about the length. Did you say you had a nicely shortened spare........?

Rod

 

4 hours ago, Rod1883 said:

Thanks for the info Peter, glad I asked about the length. Did you say you had a nicely shortened spare........?

Rod

Yes Rod

PM me your postal address and I will get it in the post to you this week.

[Rod1883]

Thanks Peter, pm sent