2021 RDX, 127k miles. Been having issues with car riding rough and jerking for a while. Thought it was spark plugs and engine coils. Replaced both of those and problem came back within a week. Had a cracked radiator that leaked all antifreeze and car overheated one time. Radiator has since been replaced and have not overheated ever since. Could this have caused gasket to blow? Dealer just quoted me 9800 to fix this problem! Seems like a disgusting money grab to me, anybody have any insight here?

 

​​​​​​Overheating could cause a gasket to blow, as well as a cracked block. If you are not experiencing coolant loss, and your oil looks clear (not white and creamy like curdled milk), I think you should be in the clear.

Are you convinced the "rough and jerking" is an engine problem, and not a transmission problem? Can you create the jerking on demand, or is it totally random.? In other words, does it just happen when the engine is cold? Does it just happen at certain speeds? At idle? When de-accelerating?

You said the problem cleared up for a week after replacing coils and plugs. Are you 100% sure of this, or does the problem only occur once a week compared to continuously?

Has the check engine light ever come on? Have you checked for engine codes? Do you have a code reader than can read live data, and have you monitored the misfire counts for each cylinder?

 

If that is for an OEM rebuild of your current motor, than that is how the stealership operates.
If you look at the various mileage offerings on LKQonline.com below for a salvage engine, perhaps.
However, you don't mention if your location is in a major urban area or BFE, which can factor into the overall quote to source an engine.
If you can find an independent Acura / Honda specialty shop, in your area, repair price could be significantly lower?

 

I am going off what the dealer is telling me. I brought the car to them 2 weeks ago and at first they thought it was the tranny so they had me flush the fluid. Then it happened again and they decided it was the spark plugs because they were all worn out. They said it was misfiring on cylinder 4. So they swapped all 4 plugs. Now they’re saying cylinder 4 needs to be changed already and they see leak in both 3 and 4. They are saying it’s head gasket now…. I feel like they are just saying guessing at this point and I do not have the money to be playing process of elimination with them. I am in NJ and they are quoting me a ridiculous amount for labor I assume because everywhere I am looking this should cost me no more than 4k. This car is financed and money is still owed on it. Stuck between a rock and a hard place right now.

 

CEL only came on once and that was the time I lost complete control of acceleration. Had to get towed and replace spark plugs first time. Ever since then never had CEL. Diagnostics and codes all came from dealership.

 

How badly did the car overheat and how long were you driving while it was? That's the big issue.

Throwing plugs and coilpacks at it was a waste sadly.If it was a HG issue, when it was idling and jerking, was it also overheating? If you drove it and got into boost, did it overheat then? You said not at all, but just making sure it did not overheat at all.
Any more pronounced smoke from the exhaust?

Seems the dealership you are using is useless as they should have accurately diagnosed this in a few hours either way. You can try some troubleshooting on your own but it would require a little hands on knowledge and a few $$ in tools.

 

I can't edit my comment:
Does it just hesitate or jerk at idle or does it break up higher up in the RPMs?

 

There are so many unanswered questions!!!!

1) Could you be clear if the jerking occurred before or after the engine overheated?

2) So the dealer wasn't even sure if it was a transmission problem, or a spark problem. The only clue you have given us, is that the problem went away for a week after changing the plugs and coils. Did it then return after the engine overheated?

3) If you are at 127,000 miles, then you are past due for plug changes and a valve clearance adjustment. Have you ever performed that routine maintenance?

What you may not know is that the computers in modern cars can recognize a cylinder misfire, and actually count how many occurred (as I said in my earlier post). So this shouldn't be a guessing game for the dealer. It should also be easy to determine if the problem is plugs or transmission after a test drive.

If the LEAK in cylinder 3 and 4, means they performed a compression leak down test, then there could be a blown head gasket, or a cracked head, or a leaky/worn valve. To eliminate first 2 (again, as I said in my earlier post), check if your coolant level is still dropping, and check if the oil looks golden and transparent, or is it whiteish and creamy in appearance. This is something you can do in 2 minutes even if you are not a "car guy". If cylinder 4 is misfiring after the plug being recently changed, that could be an indication the plug is being fouled by coolant getting into the cylinder. Remove the plug and examine it for signs of coolant.

If the valve is leaking it could be because you are overdue for the valve clearance adjustment, or you have carbon buildup on the valves which occurs easily on these Direct Injection engines. However a valve problem is not likely to be intermittent as you described the problem. It would be really useful if you could determine if the problem occurs under certain driving conditions (as I said in my earlier post).

Without answers to some of these questions, you won't get an accurate diagnosis from anyone here. I suggest that you go to an independent mechanic with a good reputation, and get a proper diagnostic before you let the dealer replace anything based on his guesses.

 

If car overheated, head-gasket might not be the only issue. Mighty be better to put a used engine without going through a dealer.

 

Yup, Rick above asked the meat and potatoes too, let's see.

That's where I was going with asking more info about the overheating scenario too, could be block/head deck are warped too, who knows. Would need to pull head and start there.
This thread makes me thing of the old days on Honda-Tech :P

 

I've had similar "jerking" motion while driving my 2021 RDX Advance (53,000mi), typically after sitting for 4-8 hours and between 2,000 and 3,000 RPM. I've taken it to dealer and they found nothing (no codes). Coincidentally, I suddenly have milky white residue on the top of the engine. @RDX-Rick mentioned this ... what is it a symptom of?

 

Pics? Did you see this through the oil fill cap?

Sounds like Head Gasket

 

That is a symptom of water mixing with your oil.

it could be caused by a leaky head gasket or cracked block. If the coolant level is constantly dropping,that would confirm this problem. If your coolant level has never changed, you can rule out that possibility.

A more likely cause would be that you take many short trips in your vehicle and it never reaches normal operating. Water, a product of combustion, will get into the crankcase. If you continue driving until the engine reaches normal temperature, this water will evaporate and be removed from the crankcase.

If you see this milky residue, you should get an oil change because water is a poor lubricant compared to oil.

 

Thanks for the replies. I drive it 27 miles each way to work, but not every day. Now I'm curious if the "jerking" coincides with a trip after days of non-use or short use ...I'll have to take note. Attached is a pic of the white milky residue. I'll work on getting a video of the tach too

White milky engine residue

 

I thought you were talking about white milky residue at the top of the engine, for example under the oil fill cap, or on the dipstick. It would look like curdled milk.

Your image is showing dried water droplets on top of the engine cover. These could be just from road spray after driving in the rain, or possibly you have a small leak in a rad hose that is spraying on the engine cover. If you have not been losing any coolant, then that is simply road spray.

 

Yup that doesn't look like anything to worry about, pop the oil fill cap off and see what it looks like inside and on the cap.

Gotta break down the jerking more though, like when, how, etc. No CEL for misfire or anything? Might want to hook a code reader up to it and see if there any stored codes.