1. Home
  2. Chrysler Cars
  3. 2005 Grand Caravan SXT / engine detonation and some noise = ?

2005 Grand Caravan SXT / engine detonation and some noise = ?

Hi,

I own a 2005 Dodge Grand Caravan SXT / 3.8L

Last fall I've noticed some strange noise:

- it is a blowing sound (like a pressurized air escaping from somewhere)

- I can clearly hear it only from inside, with all windows closed (i.e. when no outside noise is heard)

- it cannot be heard under the hood or from outside / probably because other engine noises are masking it

- it apparently comes from where the hood release lever / parking break release lever are located, but noise source is somewhere deeper

- noise changes with engine revs not only when I step on gas, but also when I'm driving down the hill on an "L" gear, which makes revs go up without touching the pedals

It did not lead to any problems, and my mechanic did not find anything suspicious, so I left it as is (again, _since_last_fall_)

Now when summer weather finally came and it is very hot outdoors, there is a significant detonation in the engine; the hotter it is outside the more heavy detonation is, beginning from about 23..24 degrees Centigrade.

I know that one of the reasons for detonation is overheating in combustion chamber; another is lean mixture (which in turn can be caused by excessive air being sucked inside). Engine itself is not overheating; at least temperature gauge shows the same temperature as it did last summer, when everything was Ok in hot days.

Taking into account that strange noise that started last fall, I suppose that the symptoms are interconnected, provided that since last fall there were no hot days before summer.

My mechanic did his best with combustion chamber cleaner, injectors cleaner etc. etc; When a "check engine" lamp turned on I had to replace the faulty EGR valve - I was sure at that time that this valve was the main reason for the detonation, but I was absolutely wrong - nothing changed except the "check engine" lamp went off.

  • * * * *

If anybody have ANY ideas how to diagnose/eliminate the problem, I'd highly appreciate it. Or maybe just point me to the community/forum where the issue can be further discussed.

Thanks !!

Reply to
Maus
Loading thread data ...

I'd wonder about a leaky brake booster. If you hold the brakes on and turn off the engine, does the pedal effort start getting markedly harder? If that's what it is, this won't be a subtle effect: unless you've got a pretty strong leg, it'll be nearly impossible to hold the pedal down.

Reply to
Joe Pfeiffer

I'll check your assumption first thing in the morning. By the way sometimes (though not too often) I notice that braking is somewhat soft and not as efficient as it should be... Not really bad but like, you know, if rotors and brake pads are wet during a good rain. I didn't pay much attention to it, but I'll now get into it and check the brake booster anyway. Does brake booster leakage cause other symptoms like brake fluid consumption etc.? I check level periodically and it's Ok all the time...

Thanks Joe !

Reply to
Maus

Not an assumption, a hypthesis to be tested.

Brakes feel soft when wet because there's less friction. Not related to the booster.

Not the symptoms you're asking about, no. A leaky master cylinder can cause a booster to fail, but not the other way around. But a leaky booster is a vacuum leak, and the other symptoms you reported earlier (detonation, etc) could be consistent with a serious vacuum leak.

Reply to
Joe Pfeiffer

Sure, I know that. I was using this case just to explain how my breaks are behaving sometimes - in dry weather.

Reply to
Maus

Nope :( Brakes are Ok, absolutely no change to pedal feedback when I turn off the ignition...

Reply to
Maus

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.