Heating seized engine via water pump - possible?

Hi folks.

I have a DD6 which used to turn freely (spanner on pulley nut) and several years later wouldn’t (think damp got to it).

I’ve tried moving it with breaker-bar on the pulley-nut and put various penetrants down the bores to no avail.

Am thinking I could fill the water jacket with boiling water via the the water pump housing.

Any thoughts?

Dont think it will help, but can hardly hurt.

What is a “DD6?”

Daimler double six would be my guess!

Regards Gerry I

Aha!!! Shoulda known!!

Look under your trans to see if you have an access cover in the front. If so, take it off and you can see the drive plate gear that the starter turns. If not, take out the starter and you can see it. Try turning the teeth with a prybar. You will have more leverage here than on the front pulley bolt.

Thanks Rob.

A few folks have suggested that but I’m worried about breaking tooth on the gear. Some guys have suggested just cranking it on the starter. Either way am concerned something will snap

Hi Wiggles

Well the heat could make the block expand a little. I use boiling water to get oil seals out of alloy fork legs on motorcycles. They pop right out but doing them cold usually results in a damaged fork leg as they are often stuck tight.

I was more concerned about the practicalities of doing it. ie would the water leak out of some outlet I’ve not taken into consideration

Probably not a real good idea. for a couple of reasons. Short Version - for the same reason why you never put cold water in a hot engine when it’s not running.

If you’re suspect of the water pump being seized then I’d remove the belt to the water pump and attempt to turn the pulley on the water pump, while the belt is off, then I’d probably attempt to turn the engine over by hand.

if both fail, my next step would be to pop the plugs out (one at a time) and check the electrode for corrosion aka rust. if there’s moisture in the cyl, the electrode will have rust on it providing the plugs aren’t covered with carbon from burning oil, then poke a borescope (search Amazon for borescope. they can be had for as little as $15 US dollars) down the spark plug hole and look at the cyl. this works best if the piston is down at the bottom of the cyl. if no corrosion, then I’d inspect the starter to see if it’s maybe engaged to the flex plate.

Once you get the engine free; and it’s going to be sitting a bit longer, then I’d recommend squirting a little bit of lightweight oil, like trans mission fluid, or a light weight motor oil in the cylinders to keep the corrosion at bay. You’ll have to turn the engine over a revolution or two in order to coat the cylinder walls.

that’s what I’d do. what I wouldn’t do is put hot water in a cold engine. that is a recipe for disaster.

keep us posted

Do you mean to say that you have not tried cranking with the starter, Foxy…?

The warning about cranking a long doemant engine really refers to not starting the engine without some preliminaries - including turning the engine ‘by hand’. However; brief crank attempt, ign disabled, to get the engine moving (or not) is perfectly OK. Then, if the engine is turning; other preparations are relevant, like oiling the cylinders etc - and some hand turning, and changing engine oil before starting the engine…

If the engine won’t turn on the starter - it’s time to consider. But a brief cranking attempt will not cause breakage any more than brute force ‘manual’ turning…

xj6 85 Sov Europe (UK/NZ)

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Is it possible to introduce hot water via the radiator with the drains open to warm the engine? This seems like an easier and cleaner way to go. Pete

I thought the “no-no” was cold water into a hot engine??? But, I’m good at reversing stuff.

I suspect the idea is to get the bores to expand and thusly lessen the friction of rings and piston that may be keeping the assembly from turning over.

I doubt that a bock full of 212F water will “move”. All that iron?

Just possibly, if one could keep a flow of scalding hot moving through the water passages, just may be.

But, it might be too late. Even if freed, it might not fire up and if it does, just not run well.

I think the best chance of success is Paul’s idea
of “levering” the ring gear. Hmmm. the longer the bar the more torque, plus the leverage of the flywheel? The mystery is the location of the pivot ? In this case, the point/s of seizure. Bore, bearing?


you are correct Carl, it is a no no. but the same rings true in reverse. The only way this would be acceptable is if the head was off, and the water would be poured around the cyl liners. Pouring the water into the water pump will accomplish absolutely nothing except possibly crack or warp the aluminum housing.

The bottom line is this. by adding hot water or any temperature differential, you’re introducing expansion and/or contraction. Aluminum is right up there with copper when it comes to absorbing and distributing heat. through out the entire piece. Not really an issue unless there isn’t any where for the expansion to take place (bolted down) then it cracks or warps - especially cast aluminum, magnesium, and Iron. Cast aluminum is strong in compression, but has very little tensile strength; which makes it prone to cracking and breaking as does cast iron and magnesium for the same reasons. This has to do with the additives to the aluminum when casting to make the internal grain structure stronger. In contrast where as, extruded aluminum gets its strength thru the oxide layer on the outside of the aluminum - which provides more tensile strength put less compression strength. There are other factors that play into the strength of aluminum that I’m not going to talk about because I’d wear my finger tips off, and honestly who cares.

Anyway, in order to get the engine to turn over, the best way is to reduce the forces that are keeping it from turning over. Disable as any ancillary unnecessary friction (pully driven accessories), and compression - pull the plugs (I know it’s a huge PITA, but it maybe the quickest solution to the end result).

I image since the crank pulley bolt has been loosened it won’t tighten up enough. Check to make sure the bolt isn’t stretched. pull it out, and examine the threads. the threads should be evenly space. a good way to check this is run a thread chaser or nut up the entire threaded part. If the nut hangs up, or is hard to turn, then chances are the bolt is stretched. Replace the bolt.

if the threads check out fine, then I’d put A DROP of non permanent thread lock on the bolt and tighten it down to spec. give it 24 hours and the try again.

I know it’s a PITA to loosen all of the belts, by doing so, you’re reducing the amount of items that could be keeping the engine from turning over. Once the engine turns over, its a process of elimination of identifying what is one isn’t spinning. I had this issue with my XJS and the air pump. The air pump siezed. Oh, darn I had to take it off. :frowning: haha

Just curious, have you checked the oil? is there any sign of moisture on the dipstick sludge? rust? also
Pop off the filler cap, look at the back side see if there’s any signs of moisture, also take a peek at the cam, is there any rust on the camshaft? Have you pulled a spark plug to see if there is any rust?

All of the above are good indications of the internal condition of the engine.

If I was suspect of seized rings, I’d put a bit of penitrating oil down the spark plug holes.

Keep us posted

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Thanks for the detailed post Mark.

This is a long standing problem. The engine has been seized for a few years now. Water pump, manifolds etc were removed some time ago and water pump isn’t seized. I was thinking about re-installing it to simply to allow me to fill the water jacket.

I’m surprised you think adding boiling water to the block would be sufficient to damage it. I feared it would have little effect as it’s a big old lump and don’t imagine the water-jacket hold s a huge amount of water therefore assumed the heat would be lost quickly.

I’ve seen on other forums they suggest running water up to 180 degrees through a block to free stuck pistons.

If adding boiling water isn’t a good idea would it be less dangerous to fill it with room temp water then heat that with a small immersion heater?

NB the plugs have all been out for a long time and the engine has had Redex and diesel poured into each bore

I haven’t tried cranking it on the starter as I know it’s stuck and thought would damage either the starter or the ring-gear.

The manual turning wasn’t really brute force. I just pulled the lever back and forth by hand. I wasn’t jumping on the bar or hitting it with sledgehammer

It was only when someone else offered to try that the thin bolt holding the nut thing snapped. I expected this to happen but let the guy find out himself that excessive force wasn’t going to work

Hi Carl.

Thanks for your reply.

Yes the idea is just to heat the alloy block enough to give the penetrating fluids a better chance of breaking the bond that the rings have with the cylinder walls

Probably better to hook up the cooling system, then use a high-wattage block heater.

Im afraid that, even if you get it unstuck, running it may damage the rusted rings/pistons/bores.


Hi Pete55Tbird.

The radiator and castings that carry hot water to the thermostat and inlet manifolds etc are all off.

Thought it would be easier just to do it via pump housing.

Also the expansion tank and coolant cross-pipe are both badly corroded so the system wouldn’t hold water. Radiator is fine tho.

Sounds like its time to start taking it apart to be honest but trying to turn it with the ring gear should be the next thing to do prior to the strip down.

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Here’s a pic of the block as it stands

My theory is that when I degreased the engine it took away the insulating properties that all the muck had and over a cold/damp winter (with bonnet off car too) it then seized so it might not be seized very badly.

It’s not like it was lying outside in the rain with no plugs in it

I have always used transmission fluid but better/expensive products are available. tranny fluid and acetone works well on rust but not sure what it does to seals. kerosene or diesel might be safer. a few squirts will collect on the lowest point, fill the cylinder until it runs out! it has to penetrate the entire diam. of piston and then leak threw to loosen the bottom. if and when it does break free, rock it back and forth going a little more each time. even if it moves thousands of an inch, it allows oil to penetrate deeper. gentle pressure every day rather than brute force all at once. I had one I saved years ago by filling completely with diesel and letting set. today, that much diesel might cost more than new rings and gaskets.

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