Struggles to accelerate, kicking or knocking sensation in engine

MDC

MEMBER
1998 FORD EXPEDITION
0.6L
4 CYL
AUTOMATIC
300,000 MILES

I recently had my heater core repaired on my truck. It has been a couple of days since I’ve had it back and I have noticed that it struggles to accelerate when I get on the interstate it will eventually accelerate normally but once I reduce speed and try to accelerate again the same thing usually happens. I have also noticed (particularly when I am at a stop light or when I first crank my truck up and drive off) a kicking or knocking sensation in my engine. My truck sat at my house for two weeks before my mechanic could replace the heater core so I don’t know if something happened during that time frame, but it was not displaying these symptoms before I got a new heater core.

5 Replies

MOTOR MASTER

MECHANIC
279 POSTS

Hello my name is Dave.

You didn't mention which engine you have, however there is a common issue with these trucks related to heater core replacement. While it seems like it is a serious issue it sounds like it could be a simple matter of the back spark plug on the passenger side could have coolant in the hole which would cause a misfire especially at idle or low rpm. If the hose wasn't replaced or tightened completely it could have an ongoing leak which would make it continue to happen. If it's a 4.6 you would most likely have two misfires as it's what's referred to as a waste fire system meaning that plug fires along with the cylinder that it opposes in the firing order which could cause a misfire on that cylinder as well. I would suggest pulling the plug wire (4.6) or coil (5.4) and use a mirror and see if there is coolant in the hole, and I would also suggest looking to see if the hose going to the heater core, which s directly above that plug, is leaking. Then repair the leak if it is leaking and use some brake cleaner (i recommend using non flammable in the red can) and spray it down in the hole as this should remove any moisture that is remaining, if you have access to an air compressor use it to blow all the liquid out f the hole. If not it should dry pretty quickly on it's own. I hope this has been helpful and thank you for using 2CarPros.

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Wednesday, February 6th, 2019 AT 4:15 PM

MDC

MEMBER
3 POSTS

Wow, I was finally able to reach my mechanic and he said something about the spark plugs. Will this problem cause any long term damage? Or will the coolant eventually dry up on its own?

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Wednesday, February 6th, 2019 AT 5:08 PM

DANNY L

MECHANIC
5,648 POSTS

Hello, I'm Danny.

Yes, having a misfire will cause long term damage. Mostly the misfire will be sending raw/unburned fuel through the exhaust system wreaking havoc on the oxygen sensors and catalytic converters. Coolant will not dry up it's designed to withstand heat and cold. As Dave above stated if you have access to an air compressor and nozzle, blow out the spark plug tube to remove any coolant. Just adding my two cents. Hope this helps and thanks again for using 2CarPros.
Danny-

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Wednesday, February 6th, 2019 AT 9:50 PM

MDC

MEMBER
3 POSTS

Thanks. I was just driving on the interstate and it sounded like something popped off the engine and then this loud rattling noise started. The truck did not stop running but off I reduced speed and got off my exit the noise stopped.

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Thursday, February 7th, 2019 AT 1:10 PM

SCGRANTURISMO

MECHANIC
4,897 POSTS

Hello,

I just wanted to chime in real quick and say that Dave is correct. I had this same problem on my 4.6L, but mine was from the coolant crossover tube on the front of the intake manifold. The intake manifold gasket had failed, right by number number one cylinder, and was leaking coolant in number one and number two cylinders. Any moisture at all in the spark plug holes will cause a misfire on these engines.

Thanks,
Alex
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