Sad time. Had a phone call from my dad today (while in the back of my P38, fixing various issues, naturally...), and our red P38 had decided to get rather toasty, having lost all of its coolant rather rapidly.

Find it in a car park, and the drain bung on the radiator looks as if it had sheared off. Interestingly having retraced the 2 miles route from the last place it was parked up, we found no trace of a trail or puddle of coolant, leaving me to believe it was very hot when the bung let go, and left as steam. Anyway - popped into the Range and found a 1/2" BSP bung that did the job with some PTFE tape, and filled it up with water. Transpires the thermostat is stuck... coolant up to 96c and the radiator is cold from below the top tank to the bottom. I figure, the stat didn't open, temperature and pressure went up, and an overly tight drain plug let go first. Gave up and towed it home (flat towing a P38... that's a noticeable lump being dragged behind!)

Good news is, no bubbling in the expansion tank while letting it idle, no steam out the back, and no odd exhaust like noises from around the engine. The bad news is however, while it was running and way too hot, the first thing my dad noticed was it was making a loud clonking/knocking noise, and then he noticed it was hot... not sure if it was down on power or not.

The bad news now, is at any increase in engine speed, there is a strange squeal/squeak noise from the engine that is not coming from the belt, and I'm not sure what it is... I need to record it, but would anyone have any ideas what it might be? It certainly wasn't there a week ago when I last drove it.

A seized waterpump Sloth? Richard had something similar that was so noisy a few months ago.
I just don't get why the bottle cap did not open at such pressure.
Tony.

Water pump is okay, getting heat inside the car and through the bleed pipe, bypass pipe to thermostat and lpg vapouriser.

I'm not sure why the cap didn't relieve pressure. I'm only going with the theory the radiator drain was overly tight and weakened - perhaps the cap pressure relief is stuck. I've ordered a new genuine stat and bearmach cap to go on next. And a proper radiator bung :)

I'd love for it to be an ancillary making the noise, but it really sounds further back. I'll run it briefly with the belt off sometime and see if it does the same.

One random thought...

If there was no sign of coolant, or the departed rad cap... but the bottom of the rad is stone cold (because of stuck stat) then how would it disappear as steam - most of the coolant in the rad would have been dumped pretty quick and if it was stone cold, then probably wouldn't have evaporated..

I'm not saying it didn't - but also would have thought that much coolant going out hot would have made a noticeable smokescreen!

Either way - hope the noise isn't anything serious!!

Good point! That I don't know... there was no sign of anything we could see on the road or in the parking spot where it was previously parked up, but having been sat in the car park I found it in, there was a drip directly under the drain plug.

Unless it lost it before the previous stop... which is a little worrying, if it were driven for another 2 miles or so with no cooling.

I've had cars dump coolant on me twice, and both times I knew it was happening. Think WW2 Destroyer and Smokescreen.

Morat wrote:

I've had cars dump coolant on me twice, and both times I knew it was happening. Think WW2 Destroyer and Smokescreen.

All depends where it ends up leaking and what it hits on its way to the ground - I've had it happen once and only noticed when i saw the fog behind me in the rear view mirror seemed to be following me, and then smelt it once stopped as it was spraying onto the exhaust manifold from a split plastic pipe.

Well, one was HG on a Montego (!) while doing about 80 on a French motorway - that gave a small but solid looking stream of coolant smoke out from between the side of the bonnet and the driver's wing. When I looked in the mirror the clear bright French day was blotted out by an immense cloud of grey smoke.

The second time was in the Jeep when a coolant hose let go and fired the coolant straight from the water pump into the engine fan and radiator then it blew back over the exhaust manifold. That wasn't hard to spot :)

I wasn't in the car when it happened sadly, but if you imagine where the radiator drain is on the bottom - that's where it all would have shot out from, straight down and under the car. One of those things... however it came out, it wasn't noticed until it was too late.

I'll get a recording of the noise its making tomorrow night. Must remember to take a spanner with me to pop the belt off to rule out a belt/ancillary noise, but I think I'll be very lucky if that's it. My dad is half deaf, so for him to describe the noise it was making when it was overheating as loud, it must have been fairly horrendous.

A couple of thoughts....
I've never boiled a P38 with knock correction, but on other engines that I have cooked, if they lose coolant from the head area they go into detonation when the combustion area gets hot enough. This will cause the engine to knock loudly as well as the characteristic running on and rattling when the engine is turned off.
On the failed thermostat, they can also fail as a result of overheating, when the wax device that controls the opening is damaged by the heat, so the thermostat may not be the initial cause.
I'll be interested to hear the noise (belted and beltless) when you get a chance to record it. Check the viscous coupling while you're down there, just in case something's broken in there.
It's a pain when you've put as much time on the car as you have recently, but, fingers crossed, there's no terminal damage.
EDIT- viscous coupling refers to the fan clutch, not the transmission VC :)

I can't offer much on the noise until we can hear it but I'm intrigued as to what would cause the radiator bung to shear off. I can't think of anything that normal running would do to cause that to happen unless it was already damaged and the extra pressure from it getting hot (for some other reason) caused it to start to leak.

I'll get a recording tonight, with and without belt.

I can only think the drain bung must have been damaged - either far too tight or cracked, and the pressure made it pop.

Whatever the case, it'll be a shame if the engine has taken some damage internally, as it ran superbly - far smoother than mine, and with a lot more poke off the line. But it'll be fixed.

It seems my P38 has been volunteered into their next caravan holiday if its not a belt/ancillary making the noise.

Quick recording of the noise. It is not the belt or something being driven by it sadly. It is the high pitch squeak.

Something to note - when stone cold, the noise in question is not present, but as soon as it gets a bit of warmth in it (I'm talking 20 seconds perhaps), it starts doing it.

https://www.youtube.com/watch?v=3p57HQttsFQ

It seems like its originating from the centre of the engine.. if you go to either side, it sounds like its coming from the opposite side.

Not able to get it up to temperature and drive to get things properly warm, so I don't know if the loud noise is going to return yet.

I'm wondering if it could be a camshaft bearing that has spun although there's other noises there that sound like they should be there. Is that running it without the belt because the whistling type noise sounds more like an alternator bearing to me. Shame you can't go back in time and get a recording of it before it started doing it......

That's belt on isn't it? The whistle definitely sounds like something belt driven. If it is belt on, did you do a belt off recording? That'd be helpful as the whistle drowns out the other noises.
It sounds a bit "endy" to me. There's a definite knock but that could be induction noise or even not firing on all 8.

Orangebean wrote:

or even not firing on all 8.

When you rev it about 25 seconds in, it seems to hesitate a bit before the revs pick up. Although it sounds reasonably smooth, it could well be running on 7.

The whine is almost a 'standard Bosch' whine... it's the alternator bearings - mine have done it for the past 5 years without getting worse, and pretty much every Bosch P38 I've seen has had that whine to some degree or other!

I'd gotten so used to the Bosch whine I hadn't thought about it, both the red and silver one do it!

Belt was on indeed, as it was a bit warm by this point and I didn't want to run it without the water pump for any length of time. I ran it with the belt off and the noise was there again. I'll do another video tomorrow from cold with the belt off.

It does seem to be hesitating more noticeably when increasing revs slowly. Will plug it in and see if its counting any misfires, though as we saw from OBs, that might not be all that accurate!

While you're plugged in may as well pull any engine fault codes. It might have generated something on its last trip.

Taken a while to get back to this.

Today ran the engine from cold with the belt off, and as before, no noises for the first 10-20 seconds or so, and it would rev perfectly, no hesitation or lumpiness. After that though, the noise returned, and it would stumble as it picked up speed. Sure enough, on the nanocom, cyl #3 is missing when you open the throttle.

No other faults in the engine ECU though, except for alternator voltage implausible, from running it with the belt off.

In this video, the engine has warmed slightly, and is doing its squeak thing. The belt is off, so the video is short as I don't want to run with no water pump and risk further damage really.

https://www.youtube.com/watch?v=XS2OSKRp_u8

The roughness in picking up speed goes along with the squeak sound becoming audible, so I'm hoping its a slight blow into the valley. Next weekend we'll start pulling it apart. Anything else anyone can think of, or does this sound plausible?