Hello again, I've a question about my coolant reservoir, in particular, its cap. The engine does not overheat (post-radiator service).
I've done some research, but couldn't find anything conclusive specific to my situation.
Some background, then. (Skip to asterixes for the question at hand).
This started after I changed my radiator, top and bottom radiator hoses, and thermostat two weeks or so ago (@ ~274,000 km).
I drove the car a few times after that, testing the new parts. I found that the coolant was spilling from the filler neck, and the top coolant hose was collapsing. The spills took form as white/very light green spots. I replaced the radiator cap, as well as the clamps on both ends of the coolant reservoir hose. As far as I can tell (after a couple more [spirited] drives), the coolant no longer spills from the filler neck.
However, the top hose was still collapsing after the car cooled down. The bottom hose is fine.
I traced it down to the plastic tubing that goes through the reservoir cap. It has shown signs of melting. The melting did so inwardly, so from the outside, it seems fine, with the exception being the tip that goes into the reservoir.
That bit is deformed, but there is still an opening for fluid to pass through.
In addition, there were bits of debris(?) within the tubing. It was grey-ish. Mud, perhaps? I don't know.
Anyhow, several pokes with a toothpick, and a few flushes with warm water later, the tube was clear enough for water to flow out freely.
I write this because I'm concerned that it could be a sign of a greater problem.
What would cause the reservoir cap tube melting to occur? The clogging of the tube itself might've been due to negligence; the car was not looked after well/was not serviced regularly in the early to late 2010s. And then I took over.
But as for the melting...why would this be?
Before replacements, the original radiator had a leak on the lower half on the drivers' side. Thermostat was original, as was the radiator cap. The engine temperature skyrocketed once or twice a month back then. Could that be a reason for the melting?
I'm going to hazard a guess, and say that the negligence caused the blockage, which caused hot coolant (and pressure) to not be able to expand into the reservoir, and also not be able to return (or at least return really slowly) to the radiator when the engine cooled down.
(That could explain the minor difference in fluid condition between the fluid in the reservoir and the fluid in the radiator when I changed it earlier in the year; the fluid in the reservoir was in a better condition than the fluid in the radiator.)
And as a result of the blockage, this heightened continuous pressure could not be relieved, and this perhaps caused the wearing of the radiator cap and the radiator leak? Twisting the radiator cap open (when engine is cool) would result in air escaping with a hiss. Excess pressure, perhaps? This occurred less so after the fluid was changed. The leaks showed itself then [one more way for air (and pressure) to escape (and enter), I suppose].
Anyone else have another explanation? Is this indeed a sign of a greater problem? Or did the radiator, radiator cap, thermostat, and hose clamp replacements, as well as the tube unblocking, fix the problem?
Hopefully this isn't too confusing...please pardon the long post.
While I'm here, I should also add one more thing:
After changing my radiator, top and bottom radiator hoses and the thermostat, I found that my fuel economy improved noticeably. I don't quite have the numbers yet...but if you have fuel economy issues, and symptoms of a malfunctioning cooling system...
...perhaps the connection is something to consider.
[Update: 05072020, 1.17 pm]: I went for a long drive yesterday. I fueled up before the trip. I travelled a hair over 200 kms that day. 90% of those kms were on mountain roads.
The needle only dropped to the first line. Normally I'd see that needle dropping just past halfway.
Good day, everyone.
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