Start-up rattle - oil filter leak down??

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I have a 97 Rav4 with 15k on a rebuild (2L4 cylinder) Have always used quality 10w-30 and Toyota filters. If the car has sat for 24 hours, it will rattle on start-up like I have a loose rod bearing. After a couple of seconds and the oil pressure light goes out, the rattling stops and the engine sounds as if I would expect. If I stop and start it again within a few minutes or a couple of hours, it will sound normal at start up. But if it is allowed sit for several hours or over night, it will rattle on start up. Any ideas why? I believe the filter has a leak down valve in the filter. And the filter sits on top of an oil cooler. I suspected pre-maturely failed bearings or pump but am now thinking maybe it may be something else. Any ideas would be appreciated.
 

Astro14

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I would test the hypothesis by replacing the filter. Less than $10 for a good quality one. If that solves the rattle, you’ve found your problem, though, I suspect it’s not going to be a simple fix...
 

Dbsoccer

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First thanks to both of you for your responses and THANKYOU Astro14 for your service! You both touched on the filter issue but I've only every used genuine Toyota filters that I buy from a dealership (online, in quantity to keep the cost down.) I have always assume at this OEM filter was about as good as I could find and that whatever valving in the filter met OEM specs etc. But I could be wrong so please correct me if I am.

Astro14, moving away from a simple fix, what comes to mind. I've been worried about other things but have never fully understood what maintains the "pressure" normally so that the typical engine does not rattle at start-up. Bearing clearances come to my mind but the rod bearing clearances have been checked and the rod bearings replaced since the rebuild. (tricky to do with the engine in the car but it was done and plasti-gauged to boot.) Main bearings have not been touched since the rebuild nor has the pump. Pump at the rebuild was OEM.
 
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I’ve seen a lot of cars have the oil pump o-ring get bad/stiff. It aerates the oil on a dry start until it seals (probably due to a little bit of oil oozing in making a seal) and finally starts working after a couple of seconds. Try switching to a high mileage oil with a lot of seal conditioners (Valvoline Maxlife has been the best in my experience). If you just changed the oil put Liqui Moly Oil Saver or ATP AT-205 in the oil instead. They are plasticizers to condition the seals/gaskets/o-rings. That should fix the o-ring.

Also consider running Liqui Moly Ceratec or Archoil 9100 (hexagonal boron nitride).They will lubricate well on a dry startup, save 1% of fuel, and last 60k miles (even through multiple oil changes) so are economical.

And the hail mary before any expensive engine work


I’ve never used the above for an engine, but it has worked great for me using the version for automatic transmissions.
 
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I suspect something else is up beyond the filter, possibly related to a bearing.

Also, if I'm reading it correctly, you had the engine rebuilt 15K miles ago and then did rod bearings after with the engine in the vehicle?
Why did you need to replace the rod bearings after the rebuild?
 

Dbsoccer

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Thanks NewtonPulsifer. As I stated the engine was completely rebuilt about 15k miles ago. At that time the pump was replaced with a new OEM pump. I most want to know is why don't all engines rattle on start-up? Is pressure being maintained in the system? I would think not. I would think that within a few seconds of shutting any engine off the oil pressure drops to zero. So I would think that, at start-up, all engines would briefly rattle if there was not some sort of cushion between the rod bearings and the crank journals. The obvious cushion is oil. In a normal engine the oil pressure would start to rise as the engine is cranked during the starting process so is this cushion thus provided almost immediately hence no knock. But if the oil pump must prime itself before it can provide pressure there would be a lag before pressure was built that could account for the initial rattle in my engine. Maybe my pump is loosing its prime after I shut the engine off. If the rattle in my engine was due to loose rod bearings, I'd think the engine would rattle all the time.

So maybe the question is what is it about engine designs that minimize the time it takes for the pump to reach so minimum level of pressure? Is there something that hold oil in the pump and pick-up tube so it won't drain back into the pan making the priming question moot (i.e. the pump remains primed always). If the filter drains back this could account for a lag in the system building adequate pressure but I'd think the Toyota filter would have a proper drain back valve - maybe not. Since this issue started I've changed oil and filter several times. Does someone have a brand of filter I could try to see if my assumption about Toyota filters is correct. This could be a bad assumption.
 
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The issue I see (which you may or may not have) is due to the oil pump flailing in those first couple of seconds if of you have a transient seal leak letting in air. Most likely at the oil pump o-ring or oil filter gasket. This is getting more common with the “newer” variable displacement oil pumps that use the oil pressure itself to regulate themselves - an engineering chicken/egg design problem. Also more likely in 6 cylinder+ engines and also louder on chain driven ones.

Yours is a belt driven 4cyl with no variable oil pump (zero for three). So that does leave the a possibility of it simply being crud buildup blocking things. 1oz of Gumout Multi in the oil per quart of oil would answer that question.
 

Dbsoccer

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I suspect something else is up beyond the filter, possibly related to a bearing.

Also, if I'm reading it correctly, you had the engine rebuilt 15K miles ago and then did rod bearings after with the engine in the vehicle?
Why did you need to replace the rod bearings after the rebuild?
Ahh.... great question. So on to more of the story. During the rebuild I used my normal pre-lube for bearings (lubri-plate -maybe old school,ok) and moly for the valve train parts. Unfortunately due to issues outside my control I was not able to drain and replace my initial charge of oil before the engine had more miles on it that I'd like to think. I don't recall exactly how many but I do recall the oil that I drained out was nothing like any oil I had seen before. The viscosity was, let's say, very thin.

So when this rattling started I thought maybe my waiting to long to replace the start-up oil caused pre-mature failure of the bearings. Since there was a rattle I first suspected rod bearings. And because I could replace the rod bearings without removing the engine, I replaced them. The one's I took out did not look trashed and the there was no metal transfer to the crank shaft but I replaced them anyway, checked the clearance with plasti-gauge and all seemed fine from the perspective. But, alas, the rattling on start up continues. It could be the mains but would require removing the engine and this is something I'd like to avoid doing unless I can convince myself this is the cause. Pragmatically thinking, if the less than ideal oil were to cause premature bearing failure, I would think the rods would go before the mains would go. And since the rods were fine when I changed them I feel the mains would be the same and I would have wasted a major amount of effort removing the engine. (This is small car where you drop it out the bottom after removing most of the suspension system.)

So I'm trying to understand so basics like why don't all engine rattle at start up? They have immediate oil pressure (albeit not full pressure) when first turning the engine over. So this means, and I'm thinking out loud, that the pump is primed and the oil filter is not empty, etc, so the oil flow goes right to the bearing clearances.
 

Dbsoccer

Thread starter
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The issue I see (which you may or may not have) is due to the oil pump flailing in those first couple of seconds if of you have a transient seal leak letting in air. Most likely at the oil pump o-ring or oil filter gasket. This is getting more common with the “newer” variable displacement oil pumps that use the oil pressure itself to regulate themselves - an engineering chicken/egg design problem. Also more likely in 6 cylinder+ engines and also louder on chain driven ones.

Yours is a belt driven 4cyl with no variable oil pump (zero for three). So that does leave the a possibility of it simply being crud buildup blocking things. 1oz of Gumout Multi in the oil per quart of oil would answer that question.
I wonder about crud build up as the rebuild is so recent and the oil and filter is changed every 3,000 miles. But I do wonder about the pick-up tube connection between the tube and the pump. If this was bad the pump could suck air I guess or the tube could drain back. But do the pick-up tubes generally remain filled after the engine is shut off? This could lead to the time to prime versus no need to prime question. I recall the pick-up tube being rather long going from the front of the engine to the rear. Again, at this point, I just trying to figure out how all this is suppose to work and I really appreciate everyone's insight and sharing of experience.
 
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I doubt it was the break in oil. Some manufacturers (like Honda) recommend keeping the factory fill for thousands of miles. I picked up my company Escape and changed the factory fill at 7000 miles.
You rebuilt this engine yourself? What was the reason behind the rebuild and at what mileage? Was there noise prior?
Did you have the block and head cleaned/checked? How did the piston rings look and cylinder walls?
Just trying to get as much info as possible.

As others have mentioned, you may need to drop the pan and check the pump and pickup tube. I don't think it's crud if it's a fresh rebuild. Machine shops typically do a very good job of returning a clean component.
 

Dbsoccer

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The rebuild was done because of leaking, primarily. The engine had a lot of miles on it but ran well. I never checked the lead down before pulling it apart but I'd guess it wasn't that bad. But there was leaking from the oil pan gasket and other gaskets (due to being dried out and cracked) so I re-built it. I was tired of the mess on the garage floor and the driveway. There was no start-up rattle at this time. The entire engine was pulled down. The freeze plugs from the block removed, the block boiled by a quality shop. Block was checked. Deck was cleaned up. Head was completely done. All the normal complete overhaul things. Critical parts were OEM (oil pump, water pump, timing belt, rollers, spark plugs) Gaskets and rings were Seal-Power or something similar.

It may be the pick-up tube but I'd like to know what to look for before opening it up again. I'm not sure If I can get to the pump very easily but it is possible, I think, without taking the engine back out.
 
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Well, I would start with replacing the oil filter. That's about as much as you can do externally.
You could probably use a stethoscope while someone starts it cold to isolate the area. You could install a mechanical oil pressure gauge to observe the pressure during cold start as well. Ultimately, I think you're going to have to drop the pan and check the pump and pickup.
 

Astro14

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I know you put a plastigauge on the rod bearings, but did you mic the journals and check for roundness? What you have sounds more like rod bearing knock than anything...and I’m wondering at the cause.

The correlation between oil pressure light and sound (knock) is interesting, but every engine I’ve owned starts up without knock and the oil pressure comes up a second or two later.

Which leads me to believe that this knock isn’t an oil pressure issue, but a bearing clearance issue that’s masked when the pressure comes up.

Still, throwing a filter on there is a quick and easy way to test various hypotheses...
 
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I have a 97 Rav4 with 15k on a rebuild (2L4 cylinder) Have always used quality 10w-30 and Toyota filters. If the car has sat for 24 hours, it will rattle on start-up like I have a loose rod bearing. After a couple of seconds and the oil pressure light goes out, the rattling stops and the engine sounds as if I would expect. If I stop and start it again within a few minutes or a couple of hours, it will sound normal at start up. But if it is allowed sit for several hours or over night, it will rattle on start up. Any ideas why? I believe the filter has a leak down valve in the filter. And the filter sits on top of an oil cooler. I suspected pre-maturely failed bearings or pump but am now thinking maybe it may be something else. Any ideas would be appreciated.

With this engine using a timing belt and mechanical lash adjusters there isn't much left. What you describe is almost certainly a rod or possibly a main bearing without hearing it I really cant say but the fact the noise goes away the instant it gets oil pressure confirms it.
Even a filter with a bad ADBV will not usually make lower end noise on a modern engine in good condition, the bearings would have to be worn for that happen and should not be in 15K but try another anyway before doing an oil pressure test with a mechanical gauge.

Another possibility is you have a loose pickup or a pinched o ring on the pickup tube but the fact it has start up noise in the lower end with 15K makes that a bit of wishful thinking. Was this engine quiet when you first did and if so has it gotten gradually worse.
Hook a mechanical gauge to it, let it get overnight cold then have someone start the engine, it should almost instantly show movement of the needle. Any lag much longer than a second then a sudden jump in pressure is not right.

Did you change the bearing size based on the plasti gauge or just replaced them with standard size?
 

Dbsoccer

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Thanks for the response. The initial set of bearings were selected based on actual journal measurements and then checked with plasti-gauge during assembly. The replacement bearings were selected based on the bearings used at the rebuild and plastigauge was used to confirm that the clearances were correct. The amount of rattle at a cold start up has not changed over time.
 
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Plasti-gauge is not very good or very accurate. I tried it once over 40 years ago and compared to proper measuring tools it was way off.
I guess what I am trying to find out is are the bearings standard or over/undersized?
 
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Dumb question--what is the oil pressure while running? Pressure is not lubrication but all the same, if it's got low pressure at idle, low pressure all the time, or it drops pressure as the oil heats up on a long drive, all would give indication as to what is going on (excessive bearing play).

Just to play differential diagnosis, no chance it is a heat shield or the like? It sounds like it needs to be cold and drained down. But sometimes noises can be buggers to figure out.

3S-FE, right? Should be crazy easy to change the oil filter on this--I do my 5S-FE when the engine is cold due to proximity to the exhaust. I wonder if it's worth letting it sit overnight, swapping in a better filter, then taking a screwdriver and puncturing the old filter. If it's dry then that might be the issue.
 

Dbsoccer

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Good questions and a great suggestion. I'm about ready for another oil change. While I don't like to change oil when it's cold, in this case, it may be worth it. I'll change it first thing in the morning and check out the old filter. Simple. I need to look at some actual pressure stuff before I go much further. The filters I use are Toyota made in Thailand for Denso so I think they should be up to Toyota's standards. But poking a hole will let me know. The thing with this filter is it sits on the side of the block with the bottom of the filter being the lowest point. So if the drain back is not working it will empty itself. Thanks for the tip!
 

Dbsoccer

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Plasti-gauge is not very good or very accurate. I tried it once over 40 years ago and compared to proper measuring tools it was way off.
I guess what I am trying to find out is are the bearings standard or over/undersized?
Hi Trav, I don't recall what beings for sure but I think they were standard. I don't recall the machine shop turning the crank. Good to hear about your experience with Plastigauge.
 
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