Starting engine for first time since valve job

[Gareth Randall]

When I start my 4.0L Jeep engine for the first time since it’s had a valve job, how much scary clatter should I expect, and how long should it go on for? Just a few seconds, or can it last minutes?

Also, I understand that I should let the engine run at a fast idle, roughly 1200rpm, for up to 20 minutes to help everything bed in. Is that correct?

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[college man]

[quote=”Dunebasher” post=93382]When I start my 4.0L Jeep engine for the first time since it’s had a valve job, how much scary clatter should I expect, and how long should it go on for? Just a few seconds, or can it last minutes?

Also, I understand that I should let the engine run at a fast idle, roughly 1200rpm, for up to 20 minutes to help everything bed in. Is that correct?[/quote]

Its no different than doing an oil change. A few seconds for the oil
to get to the head. There is no break in that I’m aware of for a valve
job. A cam yes. valves no.

[Lorrin Barth]

I’ve had them clatter for half an hour gradually getting quieter.

[Gareth Randall]

Cool, thanks. The reason I asked about break-in is that I replaced the lifters as well, and read somewhere that they need to break into the cam.

[Lorrin Barth]

Yes the do. Did you check if the old ones had a swirl pattern on the bottom. If not that means the cam is worn flat and will cut up a new lifter.

Other than that assembly lube or plenty of oil on the cam. Don’t drive at steady speeds for a few days.

[Author]

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