overheated and radiator blew out today

[c4racer]

on my wife's P5 while taking 3 kids home from school on the freeway. Nice. The heater had been acting up, so I was just about to replace the thermostat - seems these don't last all that long, I think this is the second to fail. Car has nearly 120K miles at this point. but this time when it overheated the radiator blew out - leaks water all along the top section.

So I'm hoping a fresh thermostat and radiator will fix the issue and get the car back to normal. She said she pulled over and got the car shut down as soon as possible and before the needed had pegged to the H. But there was not much water left in that system - I supposed it drained out of the radiator even after the car was shut down.

this time I'll put on fresh hoses just for good measure. Anything else I should replace while I've got it apart?

Hey - at least the radiator is pretty easy to change in this car.

there was some rust in the water which seemed a bit odd - not sure where that came from. I don't think I ever used tap water to flush it, but honestly don't remember 100%. Normally I use only distilled. The coolant was pink - not sure what type I used, also seems strange as I would normally put the green stuff in a car like this. I need to go see what is left over in the garage maybe that will jog my memory. It was last replaced at aprox 70K miles. I think this time I will flush it out several times with a mixture of antifreeze and distilled, or maybe just run a bunch of distilled through it until it comes out clean and refill the portion that drains from the radiator with antifreeze.

 

[Mike R]

224K and I'm still on my original T-stat. Sounds more like the rad failed from something.

 

[sephiroth]

rust accumulation will degrade cooling ability. you can replace the radiator and thermostat, but I'm betting the heatercore is compromised and probaly the waterpump too. flush it with lots of coolant before setting off again.

 

[c4racer]

224K and I'm still on my original T-stat. Sounds more like the rad failed from something.

the original thermostat failed at 80K-90K miles. This is not uncommon. I am surprised to see another one fail, although it could have just been the radiator that blew out this time and not the thermostat.

 

[c4racer]

rust accumulation will degrade cooling ability. you can replace the radiator and thermostat, but I'm betting the heatercore is compromised and probaly the waterpump too. flush it with lots of coolant before setting off again.

it's strange - I don't know where the rust would be coming from. Could it be from a bad heater core?

I will flush with a bunch of coolant / distilled water mix.

Water pump will be replaced soon - need to do the timing belt.

 

[P-Funk!]

A failed thermostat would not cause the rad to fail (it fails closed and the coolant CAN't get to the rad). I say the rad failed (or a hose). Unless you see (or can confirm) a hole in the rad - i would have it press checked.

I would not replace the thermostat until after you swap the rad and confirm the thermo is bad too.

 

[c4racer]

A failed thermostat would not cause the rad to fail (it fails closed and the coolant CAN't get to the rad). I say the rad failed (or a hose). Unless you see (or can confirm) a hole in the rad - i would have it press checked.

I would not replace the thermostat until after you swap the rad and confirm the thermo is bad too.

Well - I know the radiator blew because it leaks water out of the top section very badly. I suspected the thermostat because the heater was acting up recently and would intermittantly take a long time to heat up. And other times would work normally. So the radiator blowing could have been unrelated to the thermostat - true. Hoses were all fine.

But for good measure I am replacing the rad hoses and thermostat along with the radiator. No reason not to replace the thermostat.

 

[P-Funk!]

Change the rad cap too. It should not have built up enough pressure to blow out like that...

 

[c4racer]

now motor doesn't start....

True - but I have bigger problems right now. I got it all buttoned back up and it doesn't start. Cranks and almost tries to catch, but no go.

Bad things coulda happened. Not sure where to start on that....

Any idears?

 

[pasadena_commut]

True - but I have bigger problems right now. I got it all buttoned back up and it doesn't start. Cranks and almost tries to catch, but no go.

Bad things coulda happened. Not sure where to start on that....

Any idears?

It may have posted a code when you did that. Get a code reader and see if the car will tell you what's wrong.

Did you disconnect any wires when working on the radiator, if so, verify they are back on properly.

 

[c4racer]

It may have posted a code when you did that. Get a code reader and see if the car will tell you what's wrong.

Did you disconnect any wires when working on the radiator, if so, verify they are back on properly.

the only wires I disconnected were to the elec fans. Nothing else in the area really. I opened up the valve cover and all looks OK in there - timing belt is intact, valves all appear to be normal. So seems nothing catastrophic happened at least.

I checked all the fuses - looks OK there.

I guess I need to start with fuel and spark and go from there. I will grab a code reader too to see if any codes are stored that would help me diagnose it - good suggestion.

 

[p5r]

check compression. I bought my car with a blown engine. it was overheated. It bent all the exhaust valves. 0 compression

 

[c4racer]

check compression. I bought my car with a blown engine. it was overheated. It bent all the exhaust valves. 0 compression

yup indeedy - blown headgasket.

Compression
100 55 55 75

Across the block. Head contracts and bends up in the middle and the gasket blows. Hopefully nothing else. The valvetrain looks intact from up top.

But the head has to come off - I will get it to a machine shop to see how badly it warped and if it can be surfaced.

Go from there. Could end up buying a whole used engine or something.

I guess I'll dig in and do it myself. Once you go thru a shop you are somewhat committed and I would rather leave my options open. And not spend a bundle of cash on fixing a head when a used engine may end up being cheaper. Can't be hard to do an engine swap in these cars. BTDT on countless cars I think my first motor swap I did when I was 16. 25 years ago. haha.

 

[P-Funk!]

A long block will probably be cheaper in the long run (esp. with less miles). No aftermarket heads that i am aware of...

I am truly sorry to hear about your loss.

 

[c4racer]

sh!t happens, ya know?

thanks tho.

used engine may be the best way to go, but if the head is OK with a surface that is the cheapest way to get it back on the road. Assuming no labor costs other than machine work.

I did find a salvage title 2003 P5 with 69K miles and a 5-speed. If I can get that car cheap enough it might be worth the hassle to snag the motor and part it out - the 5 speed as a swap kit is worth something. Keep some spare parts for our car.