Strange rapid honking like noise on cold start

Ejforan

Ejforan

TJ Enthusiast
Supporting Member
Joined
Jun 5, 2018
Messages
247
Location
Washington state
I was road-tripping with the jeep a couple days ago and after the first day the jeep started to make this weird noise. It goes away after it warms up and hasn’t affected performance as far as I can tell. It is coming from the passenger rear of the engine bay. Has anyone experienced this before? It is a 98 automatic 4.0.
 

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Weird noise , my only suggestion is to remove the serpentine belt to eliminate noises from any accessories as a place to start.
I hope you find the problem @Ejforan !
 
Zorba said:
Sounds almost, but not quite like an OPDA, but wrong year for that.
Click to expand...
The jeep isn't a late model so I wasn’t thinking of that. I haven’t gotten to test but I plan to spray some wd40 into the distributor to see if the baring may be going out. Today I started the jeep when it was around 70 and the jeep was in the sun. No noise at all.
 
ColoJeep said:
Weird noise , my only suggestion is to remove the serpentine belt to eliminate noises from any accessories as a place to start.
I hope you find the problem @Ejforan !
Click to expand...
I most definately will do that when I get the chance. It sounds very far back in the engine bay right around the area of the distributor so I am going to start with that and go to the belt next. Videos I have heard of the distributor going out didn’t sound the same but it was the same beat. It still is a jeep and loves to make interesting noises so that definitely isn’t rules out.
 
Zorba said:
Sounds almost, but not quite like an OPDA, but wrong year for that.
Click to expand...
Hows the 98 oil pump drive work? thats an OPDA noise for sure!
If the Dizzy is cam driven which I dont know? then I would say its possibly the oil pump drive.
What 05/06 haters forget is a lot of TJ,s survived the non greased bearings at the top of the OPDA but have totally forgotten about the cam gear to OPDA gear and oil pump flat drive!
My OPDA sounded same as OP,s noise and from same location but the bearing was free and spinning after removal.
The OPDA gear is harder steel than the cam gear so over time even the "Revered" 04 will wear, its just a total bad design, simple but bad. :)
 
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Fishtaco said:
Hows the 98 oil pump drive work? thats an OPDA noise for sure!
If the Dizzy is cam driven which I dont know? then I would say its possibly the oil pump drive.
What 05/06 haters forget is a lot of TJ,s survived the non greased bearings at the top of the OPDA but have totally forgotten about the cam gear to OPDA gear and oil pump flat drive!
My OPDA sounded same as OP,s noise and from same location but the bearing was free and spinning after removal.
The OPDA gear is harder steel than the cam gear so over time even the "Revered" 04 will wear, its just a total bad design, simple but bad. :)
Click to expand...
The OPDA is connected with the distributor as far as I can tell. I drove a solid 400 miles after the noise started because I had to. Oil pressure was normal and the sound was gone before I even hit a main road. Does anyone know if the OPDA will make noises only when its cold?
 
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