Should I dump some oil over my new cylinder head?

[Gareth Randall]

Last summer I had a valve job done on my Jeep 4.0L cylinder head. Since coming back from the machine shop it’s been sat on the back seat of the Grand Cherokee it came out of and I’m only just now getting around to reinstalling it.

I’ll be putting some assembly paste on the ends of the pushrods, rockers etc when I reinstall.

But once everything’s bolted back up, should I dump some oil over it to lube up the springs and rockers before I put the valve cover back on? Or is it fine to leave it to get oiled the normal way by the oil pump when the engine is running?

Also, I’ve been told that I should expect a scary amount of clatter and probably some smoke when I first fire it up. Is this correct? As you might guess, I’ve never replaced a cylinder head before.

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[Lorrin Barth]

I would

[Jonathan Stiver]

Would be a good idea, can’t hurt. You may also want to crank the engine a bit with the fuel pump relay pulled to build oil pressure before firing it up if the engine hasn’t been ran in that long.

[Nathan]

Absolutely.
I wouldn’t ‘dump’ it all over the place, rather try to aim it over the springs and let some sit on the rocker arms. The only time an engine sees wear is during a cold start. If your dry starting and its literally dry, yes your going to hear some scary clatter and see quite a bit of smoke. As the pressure builds and works its way up it’ll calm down a bit while the ECM negotiates the proper fuel/air mix.

Remember that a new head has new clearences so you’ll have a better oil pressure (hopefully) and it’ll take your system a bit to readjust.
Let it idle for 25 minutes or so, DO NOT rev the engine during the wait. After 10-15 minutes have passed bring it to 2k rpm gently to feel her out. Don’t go over 2500k rpm until your ready to test drive. Listen to your timing to make sure everything is set and good before you take her out.

Another tip is to pull the fuel relay or unplug the injectors and crank it for 5-9 seconds to get pressure up that way, but stiv625 already mentioned that 🙂

Good luck and congrats on your first head job! :woohoo:

[EricTheCarGuy]

Yes, very good idea. And yes you will likely hear a lot of noise on start up. To help prevent that you might disconnect the ignition and hold your foot to the floor on the gas pedal when you start it up for the first time. This will shut off fuel to the injectors so you can crank the engine and prime the oil before you try and start it for real.

Good luck and keep us posted.

[Gareth Randall]

Thanks guys. I’d heard the tip about pulling the fuel pump relay and cranking the engine for about 10 seconds just to build up oil pressure first. With any luck, everything will go back together this weekend, then it’s crossing fingers and hoping… :unsure:

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