Coolant Fun

[zak99b5]

I noticed evidence of copper Stop Leak in the previa I just bought. So I decided I'd flush it out today.

Drained the radiator. Then tried the block plug. It was easy to remove, but nothing came out. So I loosened the thermostat cover, and the rest of the coolant drained.

Filled it with water to rinse out the system. But it was overheating. Bottom hose off the radiator was cold. Thinking it might be an air bubble, I tried to refill and bleed a few times. But no luck. Cold lower hose.

Decided to remove the t-stat and replace the cover. Filled it with water, and ran it for a bit. Good coolant flow; lower hose got warm.

Popped the t-stat into a pot of water and turned on the heat. It opened just a little bit when the water was boiling--maybe 1/4 inch? It was also coated in stop leak.

I Am hoping that the t-stat was sticking closed/not opening enough. My wife did say the temp gauge rose when she was driving it (we've only gone about 150 miles so far).

Flushed the cooling system till the water was almost crystal clear by disconnecting the upper hose only.

Going to to get a new t-stat tomorrow.

[TheMAN]

I hope you used flush agent when flushing the engine
that stop leak crap is so good, it'll stop up the radiator too! lol

[zak99b5]

I didn't use any chemical. Just lots and lots of water flowing through the entire system, in both directions, till the water was clean, with only 5 or so flakes of copper in it. The coolant that was in there was slimy, smelly, and an opaque orangish-brown.

I am also expecting to need to flush it again in the summer, and that should get the rest out.

This is all begs the question as to why the stop leak was in there to begin... Is there a head gasket leak? That, of course, is the worst-case scenario. But the oil is fine, and there's no smell of coolant in the exhaust, and only typical white smoke at start-up from cold.

[zak99b5]

Replacement FLAPS t-stat (Stant) didn't have the jiggle valve, so I drilled a hole slightly smaller than what was in the t-stat I was removing.

Got it in with a new gasket and filled the radiator, using the hole the top hose connects to. Then I filled that hose with coolant. Connected the hose and filled the pressure tank.

Let it it idle for a bit, revving it occasionally to speed up the water pump. Finally got heat, and I heard the knocking sound of air burping up the top radiator hose.

Topped it up a few times, then took it on a drive. Gauge held steady. Engine didn't start to overheat. Bottom hose felt pretty cool, but the top hose wasn't super hot, either. So I believe it's all good.

Going to let it cool off completely, top up if necessary, then take a longer drive soon.

[zak99b5]

Drove it for over an hour. Temp was rock steady.

But it the trip revealed that the front left brake is dragging.

[zak99b5]

Caliper was stuck hard on the slides. Had to use a hammer to beat it off (hehe) the top pin--took over 1/2 an hour.

Cleaned and lubed up the slides, and while they moved much better, they weren't really free.

Test drive revealed that that the caliper is still dragging. It gets worse as it gets hot.

[TheMAN]

I didn't use any chemical. Just lots and lots of water flowing through the entire system, in both directions, till the water was clean, with only 5 or so flakes of copper in it. The coolant that was in there was slimy, smelly, and an opaque orangish-brown.

I am also expecting to need to flush it again in the summer, and that should get the rest out.

This is all begs the question as to why the stop leak was in there to begin... Is there a head gasket leak? That, of course, is the worst-case scenario. But the oil is fine, and there's no smell of coolant in the exhaust, and only typical white smoke at start-up from cold.

if you want to flush it good, you need to use a flushing agent... straight water doesn't work good enough to get rid of stuck on mess... there's a big difference, I know

[zak99b5]

I agree. I just am more worried about why it was in there in the first place. It may well have a blown head gasket. Do those go in na Previas before 200k miles? I have 178k.

But if that is indeed the case, I want to get that sorted out first.

[zak99b5]

Maybe I shouldn't have drilled a hole in it. Temp was a little below the midpoint today as I was driving. Guess I will get a Toyota thermostat in the summer and change out the coolant again, as I was already planning anyway to get more of the crud out.

[TheMAN]

they can go any time if the previous owner neglected to maintain the van and let the coolant go bad, rusting it out and causing all sorts of cooling issues

[timsrv]

they can go any time if the previous owner neglected to maintain the van and let the coolant go bad, rusting it out and causing all sorts of cooling issues

The longer coolant stays in the engine, the more acidic it becomes. The more acidic it becomes, the more it eats away at the materials it's exposed to. The softer gasket material is usually what gets eaten up 1st. If coolant is to remain in service longer than 3 years or 30k miles, it should be ph tested and replaced when it starts becoming acidic and/or discolored. Only use high quality coolants that meet or exceed manufacturers recommendations. Never mix different types of coolant. I prefer pre-mixed coolants, but if you use concentrate only mix with distilled water. Never use additives like "head gasket in a can" and/or other stop leak products unless you're trying to squeeze the last few miles out of something. If it's something you plan to keep there will be a price to pay later. These are my personal rules developed over years of observations and experience as a mechanic. Tim

[zak99b5]

That's been my philosophy as well. As soon as I saw this coolant, I knew I had to change it out ASAP.

I have mostly owned VWs, which have special coolant needs, and adding different coolants can cause gelling and plugged heater cores.

I remember in in the mid 90s when I bought a Camry. I think it was a 90? Second generation, anyway. When I checked the coolant and saw the dark red color, I thought I just bought a car with a blown head gasket. All my experience prior had been with the standard green coolant. Imagine my relief when I learned that Toyota coolant was supposed to be red.