Core Plugs

Hi - I've just had my exhaust manifolds welded up and skimmed and was refitting them this evening when I noticed that the middle core plug along the side of the engine is weeping. I assume this is pretty serious and I shouldn't ignore it. How easy is it to change a core plug with the engine in situ?   Thanks, Mike  P.S. 1964 TE21 saloon Posted by Mikee 24/04/2014 21:47:43

Mike,  Yes it is serious. Any significant loss of coolant will result in rapid overheating and may result in significant damage. Assuming that the manifolds are off the task "should" be quite straightforward. I am speaking from a TA21 perspective where there is more room to move in the engine bay. It is worth replacing the set if you feel that they are the same age and made of the same material. (I assume here that yours are not made of brass) I replaced mine with brass. To remove the old plugs I drilled a hole into each and screwed into each a self tapping screw. With the aid of a claw hammer I used the claw to pull the plug out. I then cleaned the surface of each hole with wet/dry sandpaper.   The core plugs are not the typical ones used in the 60's that had a lip and required tapping into place. Alvis used domed discs for want of better terms and these fit neatly in the plug holes but will fall out if not kept in place. (I used some sealant to keep them in place) To anchor them tightly they need to be struck in their centres, this then flattens the dome and expands the plug thus fastening it in place. By definition they cannot be subject to high pressures as in more modern cars. If my memory serves me correctly your radiator cap is about 4lb pressure rated.  What you have to decide is whether you have the leverage to strike the plugs with sufficient force as to flatten the dome. Could this be better achieved with the car on a hoist and you working from below?  With the TA21 I had no problem striking the plugs.  Luckily there are no plugs facing the firewall.  With all that said the removal of the plugs affords a good opportunity to flush out the detritus that builds up behind them and in the passages. Much has been written about the benefit of an old hacksaw blade as a tool to push in between the cylinders. You should consider removing the aluminum lower radiator elbow and clean that area as well. In the TA21 there is a little water return hole at the back of the opening towards the carby side and this has a tendency to block ( I expect that yours may be the same - not sure). I used coat hanger wire to prod around and eventually to open up the hole.   I hope this helps.   Regards  Richard Posted by RichardWallach 25/04/2014 00:33:02

Thanks, Richard - I'll give it a go. Cheers, Mike   P.S. What should I hit the plugs with - a rounded hammer? Posted by Mikee 25/04/2014 21:36:36

Mike,  As you may come from an awkward angle a ball peen hammer may slip to one side. That said try it first.  On my TA21 I did the work from above and  found that I did not have sufficient swinging room. All I had was a long  screwdriver in the tool box. I used it against the plugs and hit the end with the hammer. It is not a pretty sight as the plugs have "sharp" strike marks on them, however they are hidden from view and it worked. What this means is that you may have to experiment.  Good luck. Richard Posted by RichardWallach 26/04/2014 00:05:35

Mike   You can get sets of plugs from RT,C Prince and ebay. On a TE the least difficult place for access is probably via under the wing ,try using a round drift and a heavy short handled lump hammer and hit them really hard,as the dome must flatten to get a seal.Not easy in the restricted space.The small transfer hole hidden by the lower water elbow is critical and worth checking that it is clear.  Good luck Peter Posted by Peter Martin 26/04/2014 09:02:40

Mike,  That little hole as we both mentioned is at the 3 o'clock position. I made sure that the coat hanger that I used went well and truly up an around in order to free any detritus.   With respect to coolant have a look at the recent posts. I have had very good results with  Penrite products.   Richard Posted by RichardWallach 26/04/2014 09:43:14

Weeping 'Welsh washer' (for I now know that they are not core plugs!) - has been removed and some brown muck removed. No evidence of any scale, but I had previously used RydLime as recommended by Guy Walker. More cleaning tomorrow and then try fitting the new plug. Posted by Mikee 26/04/2014 21:14:49

Mike,  Are the remaining plugs brass?  If not it would be well to replace them all.  Richard Posted by RichardWallach 26/04/2014 22:54:25

Thanks for the advice - it made a huge difference. I've only changed the one 'Welsh Washer' for now as I intend to overhaul the bottom end 'real soon now'! I borrowed a pressure tester from my local garage and left it at 5 psi for about 3 hours without any signs of trouble. I've also fitted a custom-made 3mm gasket on the manifolds - as well as having the exhaust manifold welded and skimmed. I finally have a quiet-ish car again. It goes in for MoT tomorrow, so fingers crossed.   Cheers, Mike Posted by Mikee 05/05/2014 21:58:13

Mike,  What was the plug made of and where was it weeping? Did you clean the little hole at the back of the elbow? Posted by RichardWallach 06/05/2014 03:29:36