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Looking through old threads, Im seeing recommendations to access a plug on the exhaust side, and other recommendations to access a plug on the intake side. Other threads say the the plug is practically immobile and its not even worth trying.
Questions:
Any consensus on which plug from those who have done it before?
Any value in running a water hose per the procedure in the manual?
If a block plug is to be removed, is there a gasket or washer or anything that needs to be replaced?
it is a 19mm or larger BOLT located behind the rear manifold on the side of the block. It is extremely tight. You can try the tire lugnut tool included with the jack to see if it is the correct size for the bolt head. You will need a hammer to smack the tool to release it counterclockwise. Very uncomfortable place to work, you will need contortions to remove it and be very careful you don't hit anything but the tool
I don't remember if there is a copper seal or not, it there is, it will come out with the bolt. On refitting the plug / bolt, apply anti- seize compound to the bolt threads.
I insert a garden hose in the fill tank and let it run water a good while with engine running, but only after I have drained all coolant, and filled cooling system with Prestone Super Flush and water and driven the car about 10 miles. Then I drain again, this time I remove the block bolt, and insert the garden hose with engine running so the thermostat opens and allows water to circulate to the engine, otherwise the thermostat will close and water will reverse out of the fill tank.
NOTE that throughout all this draining and filling, the HEATER controls should be at max temp (185), and fans in High speed so that the heater core is also flushed. This means driving the car in this hot weather with the Heater ON. I just open all windows.
Hi,
The original drain plug has a copper washer that should be okay to reuse. I had my exhaust manifolds off so it was pretty easy to remove with a socket, don't have my notes with the size.
I decided to replace the plug with a drain spigot like the early cars had. I'm including pictures of the one I used. The pressure specs are in my stored notes but I'm sure it was over 50 psi so no problems with the cooling system at 15psi max. No problems so far but I'm not responsible if you loose all the coolant & brick your engine ! I did use high temp coolant system rated silicone to coat the gasket & seal the threads just to make sure.
Cheers,
Brian Block drain is Brass plug to rear of last "freeze" plug, oil dipstick tube removed & plastic cap inserted. installed lever down to get away from exhaust
Last edited by kudzu; Aug 30, 2023 at 07:58 PM.
Reason: typos
19mm or larger, kind of flush against the block.
older Jaguar engines like the 3.4 and 3.8 liter engines had a little Tap or "faucet" instead of a bolt in the same place.
Well that was super easy. 19mm with a small breaker and it came right off. Coolant looks pretty clean as well Im beginning to think someone had this car somewhat apart in the recent past.
don't forget the anti-seize paste when putting the bolt back,, then tighten it good.
No, not antiseize, use a thread sealer like Loctitie 567or threadlocker like Loctitie 243. You want the threads to seal and to remain in place, antiseize makes it easier to work loose with vibration and doesn't provide any sealing function.
No, not antiseize, use a thread sealer like Loctitie 567or threadlocker like Loctitie 243. You want the threads to seal and to remain in place, antiseize makes it easier to work loose with vibration and doesn't provide any sealing function.
Woof- would you want to make that bolt harder to remove in the future? Id be concerned about using thread lock on a bolt I may want to remove later.
In any case, my bolt was very clean, so I just put it back in naked.
There are many different grades of threadlocker. The one I recommended is designed for oily fasteners bigger than 1/4" diameter, and is easily disassembled with hand tools. If the surfaces are clean, you could use 242, which is slightly lower strength.
An advantage of threadlocker is it fills the spaces in the threads and prevents future corrosion of the threads. The whole point of using threadlocker is so that the plug doesn't come out when you don't want it to, as the consequences of it coming out unintentionally are quite severe. Yet it also allows easy disassembly when desired.
I'm not a mechanic either, I'm a Mechanical Engineer and part of my job previously was developing and writing standards for threaded fasteners and torque specifications for various conditions to prevent unthreading under vibrating conditions.
I use thread locker, don't get me wrong, in places like the compressor clutch center bolt, and places like the license plate screws and tail light lens screws as anti-theft, I know it doesn't prevent theft but it sure makes them hard to remove. License plate theft is becoming like catalytic converter theft.
Looks like there is a very similar looking brass bolt on the intake side, a bit more forward and lower. Is that also coolant drain, or is it for something else?
Looks like there is a very similar looking brass bolt on the intake side, a bit more forward and lower. Is that also coolant drain, or is it for something else?
That should be the plug that could be removed to install a block heater for really cold climates. I've never tried to remove one but have read posts here stating that it's almost impossible to remove. Maybe they used the high strength thread locker at the factory ?
Cheers !
Which plug for draining block coolant (87 SIII)
