P38A Coolant woes

[Mark Piercy]

Oh dear! How did you manage that?

That is one thing I’m worried about, I haven’t really gotten to the root of the fat hoses. Would be bummed to replace the cooling system to find a cracked head or similar.

She's programmed and gets a little warm sometimes which led to bulging radiators. I had one pop scalding my arm... Since the alloy rad, new hoses and so on. She's cooler than Ice-cream, coffee ice-cream

 

[Scotiawhiskers]

You get engine data with the likes of 'torque', at least on the Thor engine. Coolant temp, voltage, fuel trims, MAF values and engine codes

And on the GEMS.

 

[enjoi]

She's programmed and gets a little warm sometimes which led to bulging radiators. I had one pop scalding my arm... Since the alloy rad, new hoses and so on. She's cooler than Ice-cream, coffee ice-cream

Is programmed an English word for tuned?
Well I do like ice-cream and coffee.... and there is a place down under that does all alloy rads that apparently fit the discos 2. Maybe I could find one for a P38.

As for the OBD-II shennanigans, I have an '01 P38 V8 petrol, so I was fairly confident the reader would work when I bought it.

 

[enjoi]

Also, any idea why on earth there was sand/dirt in my radiator when I flushed it out? Is that a sign of worse things to come?
I put a couple photos up on the previous page.

 

[Mark Piercy]

Ah yes, tuned.
There are alloy rads available for the 38' but I don't in Oz?
The sand could be hard water deposits my mate?

 

[enjoi]

Not sure if I'm being overly optimistic here, but it is possible that all these woes could simply be caused by my expansion tank being warped and not sealing the cap properly?
Or would that not really explain why it only overheated while at a standstill/lowspeed and was fine while traveling on a highway.

 

[Mark Piercy]

Not sure if I'm being overly optimistic here, but it is possible that all these woes could simply be caused by my expansion tank being warped and not sealing the cap properly?
Or would that not really explain why it only overheated while at a standstill/lowspeed and was fine while traveling on a highway.

Don't forget, at highway speeds you have a lot of air passing through the rad so the fan is doing very little. When coming to a standstill all that heat generated while driving still has to be dealt with, that's when the fan will come into play to replicate the air passing through the rad needed to bring the coolant temp down. Normally when cold the fan and before the engine is started the fan will be stiff. As the engine starts to spin the fan will roar for a short while and will become loose on its clutch. Then when the engine gets hot enough the fan clutch will grip and the fan becomes more and more effective to pass heat through the rad.
A none sealing coolant system I. E the cap or tank in your case will allow the coolant to boil and spew like a fountain.

 

[enjoi]

Don't forget, at highway speeds you have a lot of air passing through the rad so the fan is doing very little. When coming to a standstill all that heat generated while driving still has to be dealt with, that's when the fan will come into play to replicate the air passing through the rad needed to bring the coolant temp down. Normally when cold the fan and before the engine is started the fan will be stiff. As the engine starts to spin the fan will roar for a short while and will become loose on its clutch. Then when the engine gets hot enough the fan clutch will grip and the fan becomes more and more effective to pass heat through the rad.
A none sealing coolant system I. E the cap or tank in your case will allow the coolant to boil and spew like a fountain.

Right! So the boiling over through the cap is a symptom of a bigger issue. Like a dud viscous fan or blocked radiator as others have mentioned earlier on. A couple friendly members suggested probably a blocked rad, not just the viscous fan. If the rad was properly blocked, wouldn't I get the boiling over on the highway as well?

Looks like it’s only about $600AUD for a new fan, coupling, rad and thermostat. So I’ll just grab them, hook it all back together and do a sniff combustion type test to rule out any possibly head gasket issues too.

 

[kermit_rr]

Your fan will be fine unless it's got bits broken off or cracked. The coupling can be tested.
Thermostat could be duff, but if you don't have a problem while driving then it should be ok.
If the expansion cap isn't sealing then it could boil over at idle even if there's nothing wrong.
Mine would idle at 96-97c in the summer, that's close enough to boiling point to cause issues if there is no pressure

 

[Scotiawhiskers]

When Otto had his head gasket issue and was pressuring the coolant, it didn't come out of the cap (unless it was undone), it vented down the overflow pipe from the neck and down the inner wing.
Pressure cap is sprung to lift the inner when it gets too much pressure under it, which uncovers the vent pipe hole and opens the system. When pressure drops again the spring closes the vent hole.
So anything that stops the cap sealing tight, or a weak spring lifting too soon will vent coolant.

 

[enjoi]

The plot thickens! Or maybe it doesn’t… check out these photos I took of my fan. It has the same-shaped chip taken out of every blade in the same spot. It doesn’t look like it was done from the factory. It is as if the fan has been hitting something while it was spinning.

 

[kermit_rr]

Maybe someone has shoved a newspaper or something in it, as a test.. got a bit enthusiastic?
If it's not vibrating/noisy don't worry

 

[Scotiawhiskers]

The plot thickens! Or maybe it doesn’t… check out these photos I took of my fan. It has the same-shaped chip taken out of every blade in the same spot. It doesn’t look like it was done from the factory. It is as if the fan has been hitting something while it was spinning.
View attachment 276612
View attachment 276613

Does look like a wear mark from contact while turning, but if every blade is the same it won't affect the balance. As Kermit says, maybe someone pushed it against the back of the rad with the engine running?

 

[enjoi]

Does look like a wear mark from contact while turning, but if every blade is the same it won't affect the balance. As Kermit says, maybe someone pushed it against the back of the rad with the engine running?

Yeah it’s a strange one. The rad doesn’t look munted though, unless it was hitting the old rad. I couldn’t see it hitting anything when it was running, probably would have made an awful noise that would have been hard to miss.

In any case, I have a new rad, fan, viscous coupling and thermostat arriving this week! So will keep y’all updated in the progress.

 

[Grrrrrr]

The plot thickens! Or maybe it doesn’t… check out these photos I took of my fan. It has the same-shaped chip taken out of every blade in the same spot. It doesn’t look like it was done from the factory. It is as if the fan has been hitting something while it was spinning.
View attachment 276612
View attachment 276613

Wire not clipped in place? Thermostat housing or similar protruding?

 

[enjoi]

So I installed all the new things and it seems coolant isn’t circulating properly. I couldn’t see it coming back into the overflow tank. Well, I did see it initially, then it stopped.

Also, I seem to have completely lost power to the HEVAC unit and radio which is just amazing
So I wasn’t able to crank the heater when topping up coolant.

Wire not clipped in place? Thermostat housing or similar protruding?

Not that I could tell.

 

[kermit_rr]

The hvac radiator is always fully open, there's no valve, just flaps to adjust the air flow, so won't make any difference to bleeding the coolant

 

[enjoi]

The hvac radiator is always fully open, there's no valve, just flaps to adjust the air flow, so won't make any difference to bleeding the coolant

Ah ok. I thought I read a post somewhere about cranking hot air assists in burping coolant.

 

[kermit_rr]

Ah ok. I thought I read a post somewhere about cranking hot air assists in burping coolant.

A lot of folks do say this but i can't see any basis for it. I've never needed to.
For me, the usual burping tricks while filling, then a short drive keeping the revs over 2000 while it gets up to temp. Stop, let it cool and then top up

 

[myfirstl322]

A lot of folks do say this but i can't see any basis for it. I've never needed to.
For me, the usual burping tricks while filling, then a short drive keeping the revs over 2000 while it gets up to temp. Stop, let it cool and then top up

The basis is that in days of yore all heaters had a valve wot woz operated by a solid push pull cable wot woz moved by the heater knob or slide...

my van, being old, still has this eminently simple but reliable set-up.