Van troubles on the highway

FELICIAHARDING

MEMBER
2000 CHEVROLET VENTURE
2WD
AUTOMATIC
295,000 MILES

Hey there! So I'm on a road trip and drive a highway with a lot of hills. The van seemed to be driving great for the first leg of the trip (where it was mostly straight). I got to the inclines and the van started struggling and wasn't accelerating the way I was used to. It eventually overheated and lost speed so after trouble-shooting I needed a tow to a garage. They didn't have time to take a thorough look but determined the bit that attaches the hose to the coolant pump had broken and custom made a fitting to get by for now.

I got the van back on the highway and it felt really sketchy. It wasn't accelerating the way I was used to (seemed to not be shifting gears easily). It never overheated again (although after testing it I was afraid to use the AC because that seemed to raise the temp a lot). Engine light came on whenever I had to rev up a hill for a while (speed limit was 120) and then the oil change light came on (even though I got one right before the trip)! It was a nail-biter for the next 3 hours (lots of hills) but the handling improved in the last 45min of the trip (granted there was less incline and even some declines).

Seemed the issue was particularly happening around 80kph and once it actually got between 100-120k it was behaving a bit better (though it still struggled no matter what at time). These are slow steady inclines (mountain passes). I'm not wanting to do any major repairs as I was planning to sell it right after this trip. Am I safe to drive back? There are less inclines that way but I'm still concerned. Just puttering around town here is totally fine but there's a knocking sound that happens from time to time that sounds like it's in the passenger-side dash).

6 Replies

KASEKENNY

MECHANIC
18,907 POSTS

The oil change light coming on is just due to who ever did the oil change, did not reset the light so it went off early.

The overheating issue though sounds like a more serious issue.

https://www.2carpros.com/articles/symptoms-of-an-overheating-engine

I am concerned that the knocking noise or ticking noise is related to the overheating and if that is the case then we may have a larger engine issue.

The place that we need to start is to pressure test the system and make sure that it will hold pressure.

https://www.2carpros.com/articles/radiator-pressure-test

If it does not then we have an external leak or internal like it is leaking into the engine.

The next thing we need to check the oil level and make sure that the engine is full. If it is then we need to get a recording of this knocking and see if the knocking goes away when you raise the RPM or if it gets faster.

As for if the vehicle is safe to drive that is hard to say at this point but if it does not overheat then it would be ok but clearly we need to figure out what is going on because this has indicators of a large engine issue.

Please let us know about this info and we can go from there.

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Friday, September 3rd, 2021 AT 4:04 PM

FELICIAHARDING

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Okay, thank you very much for your feedback, this is helpful. The knocking sound only happens sporadically when I am puttering around town (at which time it doesn't have issues with keeping up with traffic at all) and doesn't happen at higher speeds. It doesn't happen very often (maybe not even every time I drive it) and it is not a ticking sound. It's almost like the sound a marble would make dropping loudly and knocking around inside plastic (but very regular/rhythmic) and usually happens twice (clunk clunk). I think it may be more likely to happen when the engine is cold and just getting going on the road but I will pay closer attention.

As I mentioned, the hose-fitting broke so that was probably the main cause of overheating (there was still lots of coolant left and it only steamed the second time I drove it, after a small top up). I know that the coolant has also become acidic (I was warned before I left but it didn't seem like it needed immediate attention). Driving it in town for short drives has been completely fine but I will test it at higher speeds again and also test the A/C now that I'm in town for a while to see if that does cause things to get a lot hotter or if it was maybe just because it was a hot day and the engine was still stressed from recently not getting enough coolant. I have an assessment booked for Tuesday so I will update.

All the best,

Felicia

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Saturday, September 4th, 2021 AT 2:20 PM

FELICIAHARDING

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*Update: I took it for a little drive and chickened out on going back to the highway but the temperature gauge did seem to be creeping up faster than normal with the use of A/C. Took it up to 60 with no issues. The knocking sound was actually happening a lot and I hadn't noticed that before the sound there was a light buzzing, almost like something winding up.

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Saturday, September 4th, 2021 AT 4:32 PM

KASEKENNY

MECHANIC
18,907 POSTS

I am not sure but I am wondering if this is detonation. That is basically unburned fuel that is igniting in the exhaust. This is due to poor ignition when that cylinder fires. Normally happens on steady inclines and steady throttle.

So is it possible to get a recording of the noise that you are hearing?

These have distinct noises so I am sure we can rule it out if we can hear it.

This can be confirmed by putting high test fuel and in the next time you fill it up and then adding what is called an octane booster. If this stops the noise then that is detonation. It will come back once the fuel grade goes back down but at least we will know what we are dealing with.

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Saturday, September 4th, 2021 AT 7:15 PM

FELICIAHARDING

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Hey! So just took it in and seemed like the gear-change issue was most likely a clogged transmission filter. Much improved after a transmission service. I'll update with anymore info. He couldn't tell what was causing the knocking sound - it's internal and they'd have to take the engine apart. So far so good though and doesn't seem to be having issues anymore with overheating. Thanks for your help though!