Please help! maybe blown rod?

I drive a 1995 isuzu rodeo and let me first start by saying a month ago i got my oil changed and found out three days ago they left the oil cap off. I know this messes with the pressure but have been riding around without it for a month and not a problem. Before I got on the road two days ago The oil level was fine, I bought a new cap to put on the engine oil filler since it had been missing for a month.

Coolant had spilled out also the day before but there was still a little left. On the way home after about an hour driving on the interstate my car started clicking and barely going when i gave it gas. The engine temperature gauge was maxed out hot as hell. I immediately pulled over and right when I came to a stop the oil light came on and the car turned off and was smoking and smelled like something was burning. after letting it sit for an hour i put coolant in the reservoir thinking it overheated. after trying to crank it ten times, it would crank but then turn off after about 5 seconds.

We finally got it cranked and it ran ok back home but the engine light remained on.we let it sit for a day and Now when crank it up the engine light doesnt come on but the oil is ok when I check it. When i crank it, it stays cranked but it makes a rattling sound and clicking and knocking. when i give it gas it sounds like it wants to turn off for a split second but revs up and the clicking or knocking or whatever it is speeds up when you give it some gas. I have not driven it anywhere. Please help.

I don’t like the sound of this.

What was the oil level when you discovered the cap missing?
What exactly was the coolant level? Is it clear?

I hate to be the one to have to tell you, but I think your engine is history. I think you’ve blown big breeches in your headgasket, I think you’ve oil-starved and overheated your main bearings until they’re rattling and binding, and I think you’ve likely warped your head…perhaps badly.

You need first to get a detailed opinion in writing from a reputable independent shop…obviously you’ll have to have it towed there. You then will need to address liability with the shop (quickie lube I’ll bet…) that did the oil change. From there you may need a lawyer, or a suit in small claims court.

Sincere best.

You haven’t thrown a rod. If I understand correctly, the oil level never went low. Is this correct? (Having the oil fill cap off doesn’t affect the oil pressure, your okay there too.)
I think that your real problem is that you massively overheated the engine due to what sounds like an unrelated coolant leak.
If so, then your head gasket is toast, and your [engine’s] head is probably warped too.
This will cost$$$.

Can you tell where on the engine the clicking or knocking is coming from? Does it sound like the area where you put the oil cap on or deeper down, lower on the motor? Is the noise clicking or knocking . . . like the difference between tapping your fingernails on the hood of your car vs. thumping a frozen leg of lamb on the floor? In any event I think MB is correct . . get an opinion from another mechanic without driving it around, I think that for whatever reason your engine needs to be looked at ASAP. How many miles on it? How was your maintenance? How often did you check your oil and other fluids? Many “off-road” miles on it? Rocketman

There’s a 99%+ probability the engine is trashed and the oil cap has nothing to do with the oil pressure unless oil is regurgitated out of the engine and the oil level gets too low. This should be apparent by an oily mess.

Something you did not mention is actually checking the oil level and from the sound of your post, you have not checked the oil level in a month. Bad habit.

As to the loss of power, that would be caused by overheating. The pistons and rings are trying to seize in the cylinders.

An oil pressure test and a compression test would verify the more than likely bad news.

Sounds like two different issues…The major overheat is the big issue…Putting coolant in the reservoir tank does NOTHING if the RADIATOR is empty…The oil cap is a diversion if it did not result in a major loss of oil…It’s hard to tell from what has been posted, but it sounds like the motor is TOAST…

Agree; with what this engine has been through, it is definitely on its last legs. All OP can do is keep the fluids topped up and hope for a few more months. Starting to fix something that age is good money after bad.