2001 Isuzu Rodeo - theories wanted!

I recently purchased my 2001 Isuzu Rodeo V6 automatic with about 132,000 miles on it. The alternator promptly went out, and I have done some suspension and other work to it myself, but I have been holding off spending any more money on it due to an issue it seems to have. The fine gentleman I purchased it from claimed to have had it for a year and everything was “in tip top shape,” though the title and test drive said otherwise (previous owner was my local police department, ownership transferred to seller 3 weeks prior). Anyway, I love a good Isuzu Rodeo (pronounced Ro-day-oh), so here we are.

My street has a steep incline and fast-moving traffic, so I often need to pull out and give it some gas to fall in with the flow of traffic. However, if I accelerate quickly from a stop, occasionally one or both (can’t tell) of the rear wheels seem to lock up, my head jerks forward, and those who weren’t already laughing at me for my $2,000 purchase then begin to chuckle. I can hear the I told you so’s coming a mile away.

I say the wheels seem to lock up because the first few times the vehicle seemed to suddenly lose power, my head jerked forward, and then it continued on as if nothing had happened. I didn’t realize the rear wheels were locking up until one day they actually screeched as if I had slammed on the brakes. My first thought was oh no, the transmission is shot, what have I done. It does have 130k miles, so the transmission likely has shifted smoother, but it doesn’t seem to have any real trouble shifting gears while driving or from P to R, N, etc., other than a loud click when shifting from park into drive (I’ll explain my thoughts on this later).

A co-worker of mine has a theory that it is a rear differential issue, and he suggested I pull the cover off and inspect the fluid and pinion/ring gears for missing teeth. I did that today and found shavings on the fill cap magnet as well as what looks like pretty old gear oil, but no particularly obvious signs of damage or wear (keep in mind I’ve never actually looked inside of a differential before in my entire life). I sewed the wound back up and currently I am waiting for the RTV to cure so I can refill and drive again. I should mention that my local auto parts store sold me a gasket, but it doesn’t fit. The guys there seem to think that my differential may be aftermarket based on an internet search of the numbers stamped on it. I haven’t the slightest idea if that’s true or not.

I did however find a good bit of play in the drive shaft. While under the vehicle I grabbed and turned the shaft back and forth and it moved a good bit before the planetary gears began to move. I believe this is the clicking sound I hear when shifting from park to drive.

I seem to be able to recreate this issue whenever I dare try, and it doesn’t necessarily need to be up-hill acceleration. The sudden loss of power and proceeding head jerk have happened on flat roads as well, but only from a stop and first gear (as far as I can tell). Currently the only engine-related issue that I am aware of is an EGR flow engine code. The tube going from the EGR valve to the intake manifold is completely and utterly clogged with carbon build-up. I haven’t gotten around to clearing it yet.

Thanks in advance for taking the time to read this. I’m open to all theories, but especially those that don’t require new transmissions or differential rebuilds. I’ve only been a knuckle-dragging shade tree mechanic for about 2 years now and I’m not up for doing either of those. Paying someone to do them seems equally unpleasant.

Do you know how to tell if your u joints are good?

The thing about forums is that one can post their thoughts even when not asked. You have just bought an 18 year old vehicle that has zero support here in the US if that is where you are . Parts are going to be hard to find and many shops will not even want to mess with this thing. You should really think about bailing before you find yourself with a 2000.00 paper weight.

I just did some reading and watched a video diagnosing bad u-joints. It is likely that one of them may be bad. I’ll do my best to check tomorrow when I go back to fill up the differential. Would a bad u-joint cause apparent loss of power symptom I described though?

As for expensive paper weights - yeah, this thought has crossed my mind as well. I’d like to figure out what this issue is first, then see about selling it. Mostly I hate that I get 18 mpg, and I don’t really need an SUV. I haven’t had any issues getting parts yet, but I can see how that could be a problem.

Is it possible since it was a police vehicle it has heavy duty parts since the part’s store did not have the right gasket?

I took the previous owner being the PD to mean that it was an impound lot vehicle for a long time, possibly involved in a crime. I’ve been looking over my shoulder ever since I started driving it.

But I haven’t seen any other signs of modifications to it. Looks pretty stock to me, but that is an interesting thought. I’ll look around with that in mind and see if I can come up with anything else.

Most police vehicle’s are ordered with heavy duty part’s

What country you in?

I’m in the USA.

In the US I am unaware if a Rodeo police package, so probably not. Go to rockauto.com and plug the stuff into the catalog and see if different options are available for rear end gaskets. Maybe more than one design of rear end?

Thanks. Could be that there were a couple differentials on these. Anyway, I used RTV so I won’t need a gasket now. I’m just hoping somebody might have an idea as to what’s causing this issue. Everything seems to point to the transmission, though I’ve never heard of a symptom like this before.

Have you driven it since fluid change?

Does it have four wheel drive that you can engage and disengage? Maybe it’s engaged. If you drive it on pavement it will feel like it’s locking up and jumping at some wheel or another.


I am going to refill with fresh oil and drive it this evening. The RTV had to cure for 24 hours.

Sorry, I forgot to mention that it’s a 2WD.