Pre-Oiler?

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In my old Explorer with the 4.0L, I'm at about 137k miles I believe. These engines are of course known to have timing chain issues.
I've heard rumblings that a pre-oiler can make a big difference in helping the chains and tensioners last longer.
Has anyone installed a pre-oiler in a vehicle or have any experience with them?
A quick Google search yields a lot of results.
I had a passing idea of installing a toggle switch for the fuel pump relay and just cranking the engine for five or ten seconds before starting it. I could do that for about ten bucks and an hour of time. It may not be the best approach for starter motor longevity though.
 
Because of the slow speed and resulting low inertia, cranking is one of the worst conditions for timing chains, the tensions can get slack and let chain slap around.

Any preoiler would need to develop at least 20 psi to begin to activate a hydraulic tensioner.

Rod
 
Originally Posted by AJB0009

I've heard rumblings that a pre-oiler can make a big difference in helping the chains and tensioners last longer.
Has anyone installed a pre-oiler in a vehicle or have any experience with them?


Yes to both ( on my own vehicles as well as industrial equipment up to units that have to preheat and circulate 8 hrs.+ to normalize tolerances before start up) I have also had to retrofit machinery for this ability.

speaking specifically for a chain to the exclusion of all other lubrication requirements of an ICE

In a car, the pre oiler follows the oil path so then the question becomes does the pump lubricate the chain directly (as most are splash/dunk)

Then the question becomes- does the lubricant from the pre oiler simply get "on" the chain ( then have to seep or work in) or can it get INTO the pins (which need the lubricant)

I have never seen a pre lube system that can inject oil into the pins of a chain.

So, in light of that and chains wear from the pins out and the sprockets wear from the snatching then later the changing contact profile from pin wear- it is VERY DOUBTFUL that a standard pre-oiler will give you any worthwhile benefit to the CHAIN/SPROCKET scenario you described.
 
Originally Posted by AJB0009
In my old Explorer with the 4.0L, I'm at about 137k miles I believe. These engines are of course known to have timing chain issues.
I've heard rumblings that a pre-oiler can make a big difference in helping the chains and tensioners last longer.
Has anyone installed a pre-oiler in a vehicle or have any experience with them?
A quick Google search yields a lot of results.
I had a passing idea of installing a toggle switch for the fuel pump relay and just cranking the engine for five or ten seconds before starting it. I could do that for about ten bucks and an hour of time. It may not be the best approach for starter motor longevity though.

all you have to do is hold down the gas pedal to the floor and it will crank until the starter burns up or the battery dies but never start. No switch needed.
 
I don't have any experience with them, only from reading about them in race engines. Where very high spring pressures and larger than the norm bearing clearances might be used--very non-production sorts of things. And maybe race oil (thin? cheap? single viscosity 30 or 40 weight?) is also used. In those cases a pre-oiler might matter (or in other cases where it was designed in, or retrofitted as ABN indicates). But in a lightly stressed production engine I'm dubious--I thought that this was what the various anti-wear additives were for, for reducing wear until oil flow is established.

I would think just changing the oil on a regular basis with the latest spec, maybe (MAYBE) avoiding the 0xW20's, and just leaving it alone until it's a problem. [I'm not sure if xW20's are a problem. Or not. But it has been debated. I believe a number of Ford's 4.6's have lived happily on 5W20. It probably is more design dependent than oil dependent. But if I was footing the bill...]

Can you inspect the timing chain tensioner to see if it's got any slack left? I think on some engines it can be checked to see just how much slack has been taken up.
 
Originally Posted by supton
But in a lightly stressed production engine I'm dubious--I thought that this was what the various anti-wear additives were for, for reducing wear until oil flow is established.


They are and they do but their effect is only fully realized in fluid film scenarios like HD/EHD and to a lesser degree on mixed boundary with scuffing.( to simplify the post I'm grouping Aw/ anti scuffing and EP additives kinda in the same bucket even though they all have different characteristics)

Specifically applied to the subject matter of the OP excluding everything else.....

A chain (either in the pin/roller area or the sprocket/roller area) by definition and the fact that neither will ever see a full revolution is always a boundary scenario.

That being said, no lubricant known to exist can overcome the mechanical forces exerted and then the two "wear" to each other ( which is why you replace the set)

Even in industrial settings with dedicated spray ( sprocket) and immersion chain lubricating systems (pins) ( which no car has)- you are only buying time depending on the sustained and/or snatch load the chain has to manage.

You have the "running" stress of the load as the link travels but when it hits the sprocket- any dimensional wear between teeth force the roller to grind against he sprocket wearing it ( very similar to 2 wrenches jacking open a padlock).

The more that wears in that gap- the exponentially wears the sprocket and flat spots the pin/roller surface each link that rolls over it

That's just the way chains wear
 
As ragtoplvr eluded to, I BELIEVE that the issue with these engines is the hydraulic chain tensioners.
So, the issue at start up is not specifically getting oil onto the chains, but rather that the hydraulic tensioners have pressure built up in them so that the chains are tight as they should be, not flopping around until pressure gets built up.
I could be off on that, but I believe that is the issue.
 
With the 4.0, isn't the problem usually with the guides and tensioners? From what I understand, the hydraulically actuated tensioners do not have sufficient oil pressure at startup and allow the chains to slap around excessively in the cassettes until oil pressure builds up. Eventually, the Delrin plastic guides start falling apart or get worn down and you have really bad chain noise. This is the reason that pre-oilers are discussed, not so much to reduce chain wear and stretch, if I understand correctly.

Our old 02 Explorer started getting noisy about 160K miles. At that point it wasn't worth sinking a lot of money into and it was a race to see if the transmission or the chains would go out first. The transmission won, BTW.
 
My 4.6 2V MGM in my sig does this if it sits more than 3 days without being driven, apparently the (plastic) timing chain tensioners bleed down & there's no ratcheting mechanism in them to stop them from collapsing. I get a weird noise for about 1/2-3/4 second on start up, then all is fine. I've wondered if a preoiler would stop this (likely destructive) phenomenon from occurring without tearing off the whole front of the engine to replace the plastic with cast iron old style ones. Thanks Ford!!
mad.gif
 
I have wondered about engine pre-oilers for many years. All of the journals that I've read say that most wear occurs at cold start but practically no manufacturers offer an engine pre-oiler that would pump engine oil through the lubrication system so that all engine parts have oil before the engine cranks. It still baffles me. Maybe the development costs are too high or the option would cost too much and not enough buyers to pay back the investment. But it really seems obvious to me, this is a problem looking for a solution.
 
I suspect that just pre-heating the oil in the pan would probably provide much of the benefit of a pre-oiler. The viscosity (in cST) of 40c oil is about a third of what it is at 20c.
 
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