Ford Sohc 4.0 - Normal or Not?

Maintenance/Repairs
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2001 4.0 on my explorer sport. During a cold start the chains make noise for 1 or 2 seconds max and then are completely quiet after that both when idling and driving at any RPM. Even if the engine is turned off after completely warming up and then turned back on 1 or 2 hours later the chains won’t rattle when started back up…

I replaced both tensioners using OEM ford parts and this made no difference in getting rid of the 2 seconds of cold startup rattle that was present before replacing both tensioners and the reason I replaced them in the first place. When I removed the old tensioners they both seemed to still have good resistance when trying to compress them compared to the new ones which indicates the old ones were “probably” still ok.

Again, after those brief 2 seconds of rattle when started up when the engines is completely cold (ie been sitting for more than a few hours) it’s quiet and it never rattles or makes noise any other time.

One other thing to note is that if I do the flooded crank start method before starting it when cold, it will NOT make the 1 or 2 second rattle. (I will hold the gas pedal to the floor and turn and hold the key to crank the engine but not turn it over until after about 10 seconds and when I see the oil pressure gauge move to the middle, I let go of the gas pedal and start it) If I cold start it using this method it will NOT make the 1 or 2 seconds of startup rattle.

Is this my guides that are broken or is this normal to have a second or two of rattle when the engine is completely cold to build oil pressure and have it get to the tensioners so they tighten up to hold the chain? I’ve had this vehicle for a little over a month now and the symptom has stayed exactly same even after replacing the tensioners and changing the oil using high mileage oil and Motorcraft filter. I just want to know if this is normal or if it’s not and I should get rid of the vehicle if a larger problem is imminent.

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If the guides were broken they would have fallen apart when you replaced the tensioners (this was a common issue early on with these engines).

The engine (I assume) is now 24 years old and has an unknown number of miles. The issue you are describing is just general wear and tear on the engine internals causing a little delay in oil pressure.

I would drive on. I drove my 2002 Explorer with the same start-up rattle up to 218,000 miles before I sold it.

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3

The rattle you hear may be from the rear timing chain.

Tester

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4

I can’t speak to your engine configuration, but I hear no timing chain-sounding noises from my 50 year old Ford 302 engine. I expect you do have some sort of problem brewing there. May not be a serious enough problem to have to do anything about it though. Not sure if the oil pressure observation is related or not.

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Here is your OHV timing chain set

627×900 57.9 KB

Now here is the OP’s SOHC timing chain set without a balance shaft…

1500×1040 155 KB

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Yes, 302 has a very simple timing chain design. Still, I wouldn’t expect timing chain noise is normal on the OP’s engine either.

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George, My history with 302 Fords with laminated chains was somewhat grim. With a manual transmission they failed at 100k +/- and with automatics they would usually survive 150k +.

OTOH, later models with roller chains would last well beyond 250k with automatics but I never ran across a manual with a roller chain.
What is your 302 in and what’s the mileage.

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With the rattle only for a couple seconds at cold start up, I’d guess lifters before timing chains.

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73 truck/200+ k. I’ve never actually seen the timing chain, but from the repair manual photos, it looks like a roller chain to me.

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I might suggest that out try a different brand of oil filter. Your filters anti-drain back valve may be allowing oil to drain back into the pan after a period of time. A high end filter with a better anti drain back valve might solve your issue.

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I would almost bet that George drives like he has a fresh laid egg between his foot and the gas pedal… and probably never gives it much over 25% throttle… so he could make a plastic chain last 500K miles… lol

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Nothing wrong with that. I have run cars up to well over 200k miles, on the original motor and transmission, by driving carefully. The people tailgating me, thinking I should “floor it” when accelerating from a standstill are not going to buy me a new transmission, when it fails, so why should I shorten the life of my car just to please them? Yeah, I can’t think of any reason, either.

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There’s nothing wrong with driving carefully . . .

Just as long as you aren’t in the left lane on the freeway driving 55mph, forcing everyone to go around you

Or even worse . . . the guys that drive so slowly, that they’re actually BELOW the minimum required speed to even be on the freeway in the first place

It is HILARIOUS when highway patrol pulls up behind these slugs and tells them on the PA system to speed up or get off the freeway :laughing:

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14

I had a 1999 Grand Caravan (bought in 2001) with the 3.3L and A604 4 speed auto… It went at least 195K driven hard, it lived a hard life, sold it to my son and he hauled papers in it filling the entire back up and putting the tires up in the fender wells, basically on the bump stops in the rear… Trans finally went at 195K plus with only one trans service when the VB died and I had a new one put in it at around 75K… Engine was still going strong… So driving it easy had absolutely nothing to do with it, nor did reg maintenance other than oil changes… Average long life on this trans is 180K… lol

I have always driven my vehicles hard with little issues on the life of them…

Throttle affects line pressure in the non electronic transmissions making them shift a little firmer, not letting them slip as much, slipping builds heat and kills transmissions…

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Maybe a bit of an exaggeration, but I’ve always tried to drive as safely as is practical for the situation. I’ll admit, I sometimes press the pedal to the floor briefly just to see what happens. I call that “decarbonizing the cylinders” …lol …

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