19 replies to this topic

[Eyeful]

I've a 1976 Leyland Mini (998cc) that's done genuine 89,000klm and thoroughly log-booked. No indication that head/block have been touched except for resetting the valves. Went to do a coolant flush and found the drain plug in the back of the block doesn't allow the flow of coolant ie it's blocked ... or seems to be. Initially had an overheating problem when country driving but no problem with heating in city driving ie short drives are OK; long drive was problem. Found small leak where heater joins drivers side of head and fixed this. Replaced thermostat and radiator cap (recommended by mechanic) to solve leakage problem. Appears leakage problem solved so did flush & refill after using radiator flush.

 

However, coolant wouldn't drain from block. Checked that I'm using the correct plug (see attached picture) and plug shows signs of minor water corrosion. Coolant is coming through very clean when flushed. Radiator, bypass hose & water pump replaced about 4 years ago. Checked flow through heater; radiator; and without thermostat ... all seem OK. No air bubbles ir oil in radiator when running. Radiator specialist advised no problem with combustion gas in cooling system. Reverse flushed radiator. Attempt to reverse flush block unsuccessful as water wouldn't enter block's drain plug. Motor is running cooler than previously but I'm aware that the temp sending unit at Cylinder 1 while drain plug at Cylinder 4 and concerned that No 4 could be overheating. No evidence of oil in coolant nor water in sump.

 

I think my next step is either removing the head or removing welch (core) plugs to find the blockage/s.

 

a) Looking for suggestions of what else I could try before removing head or welch plugs.

b) Should I remove the welch plugs or head?

c) If removing the welch plugs, should I do the driver's side plug first or the 3 front plugs (starting at driver's side)?

d) Any suggestions or advice would be very much appreciated.

 

Thanks in anticipation for any suggestions, Peter

Attached Files

•  uLHU31.jpg   69.66K   8 downloads

[GraemeC]

There is no drain plug shown on that photo - can you highlight which one you think is the drain?

 

The simplest way to drain is to remove the bottom hose - it won't completely drain the block but will get the majority out.

[MiniMadRacer]

Hi,

 

Firstly that top stabilser bush needs replacing, as its foo barred... Not  related to this issue, but needs to be replaced.

 

Get some copper wire or a welding / brazing rod and bent it into an upwards direction and push it into the drain hole in the block.. give it a good wiggle and rodding aiming to get the rod to go up inside the block, not down towards the gearbox (hope that makes sense).

 

Your blockage is prob a build up of silt.at the bottom of the block, so removing core plugs wont really help here.

[Eyeful]

Sorry I should have explained that the plug has been removed. I've attached the photo with a yellow circle around the drain hole into which the plug goes.

 

Yep you're right the engine stabiliser does need new rubbers. I also noticed it when doing this exercise. I plan to check the engine mounts as well as I don't think any of them have been replaced yet.

 

I'll try the copper wire trick and understand the need to bend it upwards to get in towards the head.

 

Good to know that removing the core plugs won't solve it. Would removing the head solve the situation?

 

Peter

Attached Files

•  uLHU31.jpg   130.92K   6 downloads

[nicklouse]

Sounds like it is full of rust flakes and other crud. 
 

lots a broddling up the drain hole and then you might need to fill the block and head with vinegar for a few weeks to dissolve the rust.

[Eyeful]

I've not seen any rust flakes but did get some crud from the heater valve when cleaning that up.

 

I've not heard of the vinegar trick! could you tell me more please? Is it white or brown or other (eg apple)? Do you dilute it or use it straight from the bottle? If so by how much? Would you put it through the entire system, radiator and all even though the radiator is copper?

 

Thanks heaps, Peter

[Aly-g]

over 1 year on with no replies ? i wonder if this was ever resolved as i am having similar problems, blocked drain plug ( i poked and prodded with wire, screw drivers and anything else that could find....! all to no avail ,the mini was running very hot etc, flushed the block as best i can then tested the thermostat which did not seem to open very much at 88c so i removed it and run without it, the car is running well without the thermostat and not over heating, so off to minispares tomorrow to get new stat and gasket and a few other bits and pieces then test, i'll let you know how it all go's.......oh and by the way the block drain plug is still blocked , i think it has always been blocked...! ???

 

 

Allan

[cal844]

over 1 year on with no replies ? i wonder if this was ever resolved as i am having similar problems, blocked drain plug ( i poked and prodded with wire, screw drivers and anything else that could find....! all to no avail ,the mini was running very hot etc, flushed the block as best i can then tested the thermostat which did not seem to open very much at 88c so i removed it and run without it, the car is running well without the thermostat and not over heating, so off to minispares tomorrow to get new stat and gasket and a few other bits and pieces then test, i'll let you know how it all go's.......oh and by the way the block drain plug is still blocked , i think it has always been blocked...! ???


Allan

If the drain is blocked then you may be able to drill the crud out gently

[Aly-g]

thanks for your reply, i just need to find a drill with a 90% turn at the end..! its a bit tight between the back of the engine and the bulkhead,

 

 

Allan

[iain1967s]

If you want to get aggressive, I got this suggestion from Spider for my overheating 1275S engine and it worked a treat…

 

First, remove the drain plug and run the car with a 25% mix of CLR Pro household cleaner and 75% water.

 

Run it at idle until it gets warm, as the pressure builds up the CLR will quickly dissolve all the crud and it’ll blast out of the open drain hole after a few minutes.

 

Caution: it’s caustic and will strip paint and skin, so protect the firewall with rags and yourself with PPE appropriately.

 

Fill the radiator with clean water and let it continue draining out of the block until it runs clear. Then switch off the engine and back flush the system using a hose pipe connected to the heater outlet with radiator cap off.

Refit the drain plug and fill with plain water, then flush again after driving a few miles to get the last of the CLR out of the system as that stuff crystallizes if it’s left in the system too long.

[Spider]

When that drain is that blocked (and it's not uncommon), I found it pointless or extraordinarily slow at best to try any kind of cleaning product until you can get some flow through it. To do that, I use a drill bit, starting off with a 1/4" and work up from that. I turn it with my fingers and it does take a while. It's also fairly deep there too. Then, after I mechanically clean it as far as I can, then I use chemicals. I was using CLR for a long time and quite happy with it, but recently, I tried another product, Liquid Intelligence, and found that to be really good, quite potent stuff.

[Tornado99]

Seems to me that using a household plumbers drain snake to run up the drain opening would be a good thing to try. These can be had in flexible springy type metal and some can be fit to a power drill.
For proper descaling of hard mineral deposits in the system, there are automotive cooling system descaling solutions available that work well, do no harm. I like the suggestion to let the system come up to temp with pressure building while drain plug is out. This may blow it clear nicely.

[Aly-g]

thanks all you lovely people out there, i gather the products mentioned are for unblocking drains ...? i will have another go at the drain plug again tomorrow , i did a run to mini spares today (Sat) round trip of about 30 miles with the thermostat removed and the car was still running to hot for my liking.... i will try all of your suggestions and fingers crossed will clear the block of all the crud, thanks again everybody i appreciate all your help, i'll let you know how it all goes tomorrow.

 

Allan 

[whistler]

https://www.screwfix...cB&gclsrc=aw.ds

[Tornado99]

thanks all you lovely people out there, i gather the products mentioned are for unblocking drains ...? i will have another go at the drain plug again tomorrow , i did a run to mini spares today (Sat) round trip of about 30 miles with the thermostat removed and the car was still running to hot for my liking.... i will try all of your suggestions and fingers crossed will clear the block of all the crud, thanks again everybody i appreciate all your help, i'll let you know how it all goes tomorrow.

 

Allan 

 

 

Quick google for images of plumber drain snakes:

 

https://www.thespruc...-snakes-2718643

 

 

You could try the plastic ones, just be careful not to get it stuck or snap it off. The cheaper metal ones should work well here if you can make it bend into the opening? 

 

Again, don't mess with homemade or household de-scale solutions when there are readily available automotive products for this.