Low oil Pressure after timing chain guide replace

Tiny
SURFSCHNAUZIE
  • MEMBER
  • 2006 NISSAN XTERRA
  • 4.0L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 140,000 MILES
History:

1. Vehicle has been running slightly hot for about two years. On occasion the A/C would shut off (I assume as a safety mechanism). Our mechanic could not tell us why, every time we brought it in, they would just add oil.

2. Then the car’s main timing chain guide broke and was making quite a bit of noise.
3. I opened the timing chain cover and replaced the water pump, all three timing chains, the main guide and the guide on the right. I purchased new timing chains so that I could see the timing marks. (I wanted to make sure it went back correctly in case it skipped) I replaced the main timing chain tension-er and the guides on each of the secondary timing chain tension-er's, and coolant temperature sensor. I replaced the radiator. I used a no spill funnel to remove the air from the coolant system.

I noticed that inside the timing chain case there was a buildup of dried oil in spots.
I replace the thermostat and the spark plugs.

4. The car started right up, but indicated low oil pressure after warm-up and makes a noise when it is warm and I hit the gas along with a loss of power. Additionally, it tends to run slightly hot but does not seem to overheat like it did prior to the guide breaking. After I put it back together I was getting the check engine codes (p0011 and p0021), which I understand might be triggered by a low pressure situation.

Things done to diagnose:
1. Pressure tested coolant system with car running and off (to see if there was a head gasket leak- it seemed to hold the pressure.
2. I re-seated the oil pressure sensor and cleaned the connections.
3. I replaced the oil cooler seal (it was leaking slightly) I cleaned around the area and was looking for a relief valve but could not find it.
4. I changed out the cam seals (I did not do that the first time).
5. I replaced the oil filter three times (the last time with an OEM filter.
6. I tested the oil pressure when I first start the car at idle of 1,000 rpm it is 40 psi and 40-55 psi @ 2,000 rpm.
after warm up
only 3 PSI @ 1,200 rpm and 5 PSI @ 2,000 rpm and noise when I hit the gas and a loss of power.

Things I suspect
1. *Oil gallery gasket failure (dried oil I the timing case).
2. Oil pump failure.
3. Clogged oil passageway.
4. Stuck or failed oil pressure relief valve behind oil cooler.
5. Stuck or failed oil pressure relief valve somewhere else (oil pump?).
6. I may have hooked a hose back up incorrectly (I do not think so, but it is always possible).
7. Timing off (I think it would run really poorly, which is not the case).
8. Bad replacement part (even though all of the timing chain components were OEM).
9. Head gasket failure (slight milky look around cap, but oil looks fine (coolant pressure test did not show a leak/ the car has been sitting so I think it just might be moisture in the system.

With the exception of number one, I am not sure why the pressure would only drop after warm up.

Things that confuse me
1. This is my wife’s car and she does not remember the gauge on the oil pressure dropping.

Tests I can still perform:
1. I purchased a leak-down tester

What do I do next? Opening up the timing case again is quite a bit of work.
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Tuesday, April 11th, 2017 AT 5:39 PM

24 Replies

Tiny
HMAC300
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You mentioned first of adding oil to what? Engine? And how much was added at each time? Due to the viscosity of oil cold/hot will make a nominal difference. However, there is a spec on the clearance of pump gears as well as relief valve. If out of whack the pump should be replaced. Also, the o-ring or gasket where pickup tube bolts to can be leaking air causing as well as what you have stated in your reply if head gasket is leaking can be source of oil leakage requiring adding. However it gets back to how much oil was added each time as it can be the bearings are worn enough with too much clearance causing the low oil pressure. I am assuming that the readings you gave are from a manual gauge.
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Wednesday, April 12th, 2017 AT 7:36 AM
Tiny
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It was engine oil that the mechanic added. 1 qt every several months. Recently, I filled the oil up and ran it and then measured the amount that I pulled out. It didn't seem like I was loosing much oil. The oil pressure readings were from a manual gauge.
Where is the relief valve located to check? I looked behind the oil cooler and didn't see it.
I did a coolant pressure test with the car running and not running. It seemed ok. Does the thermostat need to open during the test to determine if the head gasket is blown (it might not have opened during the test)?

Can we rule anything out?

What should my next step be? Leakdown test? Check the pickup tube/gasket? Find the relief valve? Open up timing cover and pull out the oil pump, check the oil gallery gasket, which is a paper gasket covering the main oil passageways in the back of the timing cover (notorious on these cars)?
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Thursday, April 13th, 2017 AT 4:04 AM
Tiny
HMAC300
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The relief valve is part of the pumps. If anything i'd drop the pan and check one main and one rod bearing furthest from the pump. See how they look or send pics back of bearings so I can give you an idea. But prior to do oing change oil filter as sometimes they are the problem especially if it's a fram, try a napa, wix, Purolator. Those seem to have less problems or a factory one. Do the easy stuff first. If you decide to do an oil pump just replace it don't mess around with checking relief valve because cold/hot they act different. You might try a straight 20w oil as well see if that changes things if it does then it's probably bearing wear
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Thursday, April 13th, 2017 AT 5:48 AM
Tiny
SURFSCHNAUZIE
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Thank you again for your help. I did try 2 oil filters, the latest is an OEM filter and still the same issue. I will drop the oil pan to check the bearings this weekend and take some pictures. Its the lower oil pan, correct? I originally didn't think it was the bearings because I didn't hear that noise at start up. I didn't see anything shiny in the oil too. I will look into anything to solve this, I really appreciate your help.

My timing case had oil (see the photo) in it and didn't look like everyone else's online, which is why I thought that it was the main oil gallery. In addition to the low oil pressure and the loss of power, It seems that my noise occurs when it is warm and I hit the gas (with a slight delay). I think i'm hearing slack in the timing chain (which is why I think that the timing chain guide broke originally). Here is a photo of the timing chain case prior to when I repaired the main timing chain guide. You can see there is dried oil in the case. I thought it was really odd when I had it open. This is why, more recently, I thought it might be an oil gallery leak causing my pressure loss.
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Thursday, April 13th, 2017 AT 4:32 PM
Tiny
HMAC300
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What you see is sludge and varnish and can be from oil used or how often changed etc. Also re reading you rfirst question it says after you replaced timing chain so I would suspect either a pump problem or partial blocking of pump pickup or an air leak there. If you take the pump off pack gears with Vaseline prior to starting as well and make sure pickup has good connection to pump. But i'd try 20w oil first prior to taking pan off see what you get there, if it still drops then it may very well be a bearing problem.
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Thursday, April 13th, 2017 AT 5:40 PM
Tiny
SURFSCHNAUZIE
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Is there an alternate to 20w that I can test with? The auto stores that are in my area only seem to carry 20w-50
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Saturday, April 15th, 2017 AT 6:04 AM
Tiny
HMAC300
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No you don't want to use 20w50 just straight 20w try a gas station 20w is pretty common. The other would be to hard on lifters and rings.
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Saturday, April 15th, 2017 AT 6:19 AM
Tiny
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20W is labeled as "non-detergent motor oil"? Is that the one?

It in't the 0w-20 right?
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Saturday, April 15th, 2017 AT 11:38 AM
Tiny
HMAC300
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Yes that is the one you are only going to use it to test and not keep it in the engine you don't want to use the 0w20 once you put the 20w oil in if you oil pressure comes up then you know it's a bearing problem if not then it's either the pump or something like that. Even if it comes up like 2 psi or so
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Saturday, April 15th, 2017 AT 1:51 PM
Tiny
SURFSCHNAUZIE
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I tested the car with the 20w non detergent oil. When cold, I got about 40 psi at idle and then it dropped to about 30 psi as I was testing. When cold at 2,000 rpm it was 60 psi and then dropped to 50 psi as I was testing. The oil pressure seemed to bounce a little.

After warm up. There was 0 psi at idle and around the same 3 psi at 2,000 rpm (same as prior to the oil change). There is a hesitant buzz/rattle after I hit the gas when warm and the psi is low. The sounds seems to come from the passenger side rear exhaust pipe before the muffler. I thought it might be an exhaust item, but it really only appears when the car is warm and when I have low psi, so I'm more suspect.

Overall, I didn't really notice a difference from my last test. In both situations the psi drops lower and lower as it warms up. I'm not sure how accurate the gauge is if we are trying to notice a slight difference, it is a new 8milelake Oil gauge- it had fine reviews for a $55 gauge online.

I see a common problem w/ this engine (VQ40DE) on Nissan and infinity is the rear timing cover gaskets leaking and causing an internal leak. I'm not sure if that is something that you have heard too. There was that timing cover sludge in the engine as I made the initial timing chain guide repair. As I was cleaning some likely drooped into the oil pan. Could that cause a blockage and this issue?

Please let me know the next things that I should test. I'm really determined to solve this. I've been at this for about 7 months. Thank you for your help.
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Saturday, April 22nd, 2017 AT 1:34 PM
Tiny
HMAC300
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I am really out of ideas from the diagram i'm sending the oil lines go no where near the rear cover so I would rule that out and I see no tips from other mechanics for this problem. If I were you and you REALLY want to put the time and energy into this then where arrows point I would look for a problem there or partial blockage. Because if it's cold and has good pressure then gets warm and drops but from your testing the second number is warm i'm assuming so with heavier oil in it drops about 10 psi so it leads me to a bearing problem. Or leaking where I've pointed out that is all I can think of. From the factory chart shows only 14psi at 2000 rpm when warm and ALL oil will drop when warm see pics
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Saturday, April 22nd, 2017 AT 3:42 PM
Tiny
SURFSCHNAUZIE
  • MEMBER
Please see this article regarding leaking oil from the gaskets in the timing cover and pressure loss.

https://www.motor.com/wp-content/uploads/2016/01/4_FOREIGN_SERVICE_0116.pdf

I did notice that there is a bit of smoke at warmup from the tailpipe when i had the 10w-30. I never did the idle relearn for the nissan (required because I cleaned the throttle body), I just assumed that the extra smoke had to do with running rich on startup. There is a smell associated with the car running, but I don't know enough to say what it is (whether it is coolant burning)- or it might be in my head. The mechanic previously said the cats are bad. Would a head gasket cause the oil pressure to act like that? I did the coolant pressure test and it seemed ok cold. Did I need to make sure the thermostat opened? Should I get one of those chemical testers to rule out the head gasket? I mentioned the cap had some milky residue, but the oil hasn't been foamy or milky.

My wife said that she would have remembered low oil pressure showing on the dash before the timing chain guide repair (it was her car)- which confuses me. It makes me think that perhaps that the issue might be caused by something I did when replacing the timing parts.

Please let me know what you think about the article w/ the internal leak or potential head gasket.
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Sunday, April 23rd, 2017 AT 5:45 AM
Tiny
HMAC300
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You can try the chemical for a head gasket as that could cause it but I don't think it is. Also all I can tell you about the internal leak try the feeler gauge thing in the article and see if it's so. If it goes through then that is where the leak is and will need repairing either with two gaskets or check for casting problem beneath the plate prior to taking it off if you can access it.
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Sunday, April 23rd, 2017 AT 8:18 AM
Tiny
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Before I move further, I was thinking about sending an oil sample in for analysis. Do you think I should? If so, which company? Will I be able to interpret the report?
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Monday, April 24th, 2017 AT 3:54 AM
Tiny
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I wouldn't bother with the oil sample I don't know where to send it anyhow. If you can see some metal chips in it then you 'll know not to bother without pulling engine for an overhaul.
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Monday, April 24th, 2017 AT 6:08 AM
Tiny
SURFSCHNAUZIE
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Ok, 3 questions before I open up the timing case again:

1. Could using an air impact wrench on the crank bolt to tighten and loosen without locking the fly wheel cause this issue?
2. At one point I noticed that one of the bolts that goes from the oil pan through the timing chain case was very loose(it was hard to reach, but I used rtv), could that cause the issue?
3. My friend suggested an engine flush for any blockage, is that worth a try? Can you recommend one?

Thanks
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Tuesday, April 25th, 2017 AT 5:20 PM
Tiny
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Donot use an engine flush it is not good for the motor. The bolt you left loose not knowing where it is could cause the problem if it went into the oil galley but not knowing which one you did leaves me not much to say about it. Unless an oring has fallen out I really am at a loss at this point
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Tuesday, April 25th, 2017 AT 5:54 PM
Tiny
SURFSCHNAUZIE
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I sent the oil oil out to a lab. They identified some coolant in the oil. Could that be enough to cause the oil pressure to go from good at cold to drop to almost nothing after warmup? Where can it leak? Head gasket? Intake gasket? What do you think?
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Saturday, May 13th, 2017 AT 4:03 PM
Tiny
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One other thing they didn't indicate bearing or ring wear.
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Saturday, May 13th, 2017 AT 4:04 PM
Tiny
HMAC300
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If there is coolant in the oil it's probably intake or head gasket due to aluminum heads on a iron block. But will it caue you low oil pressure I've never seen that happen since being a mechanic. However it will really screw up the bearings as coolant is not a good lube. And it really depends on how much coolant in the oil. Trace amount? Regardless you still have the problem i'm assuming and there has to be a reason, not being able to see this nor actually physically look at it i'm kind of stumped myself.
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Sunday, May 14th, 2017 AT 8:36 AM

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