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Gen2 3.5L Ecoboost low oil pressure after phaser install – Findings

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3K views 11 replies 5 participants last post by  Scottr22  
S
#1 ·
Thanks to all for offering so much great information on this site, as it has helped me on multiple occasions. My turn to give back.

I know this topic has been a head-scratcher for a while and I wanted to share my findings in hopes that others may avoid this problem. Please note, I realize there are multiple reasons for low indicated oil pressure in these trucks, and I have experienced three of those reasons. However, the following is why I experienced actual low oil pressure.

BLUF…..the tensioners for the Gen3 Ecoboost are different from the Gen2 Ecoboost. Some phaser kits are being sold for a 2017-2024 3.5L Ecoboost, and these should be avoided for a Gen2 if the kit contains part numbers ML3Z-6L266-A and ML3Z-6L266-B. Also, be careful as some well-meaning parts folks are providing these parts as “updated” parts because they align with the year models of the updated phasers (my experience).

Truck: 2018 F150 Platinum 3.5l 4WD, 162k Miles, Second Owner

My experience and findings;
  • I researched parts for Phaser replacement using my VIN on the Ford Parts site. I also replaced the water pump and VVT solenoids due to the mileage on the truck
    • HL2Z-6C590-A Cam Phaser Installation Kit
    • HL3Z-6268-A Timing Chain x2
    • HL3Z-6B274-A Guide
    • HL3Z-6B274-B Guide
    • HL3Z-6K255-A Tensioner Arm
    • HL3Z-6K255-B Tensioner Arm
    • HL3Z-6L266-A Tensioner
    • HL3Z-6L266-B Tensioner
    • HL3Z-6M280-A VVT Solenoids x4
    • JL3Z-8501-B Water Pump
  • I researched the cost on multiple Ford part sites and placed an order. I normally use a local Ford dealership that has excellent parts prices; however, in this case, I saved a couple hundred dollars even with shipping
  • I received and installed the parts…..this is where I went wrong
    • I did not notice the substituted tensioner part numbers until after installation
    • Note the “M” rather than the “H” in the part numbers above for a Gen3
  • The installation went great in less than 10 hours, mainly because of my very experienced son-in-law
    • Based on the scarring on the balancer and RTV on the front cover, we believe the phasers had been replaced previously
    • Old-style phasers were replaced
  • At high idle there was no indication of low oil pressure. However, shortly after the normal idle kicked in the low oil pressure warning came on
    • I had experienced low indicated oil pressure about a year earlier and replaced the sensor to fix the problem. A short while later I also had to replace the sensor wiring harness for the same reason. So I was familiar with these issues
  • I used FORSCAN to check the indicated oil pressure since the cluster gauge isn’t much help. That said; the gauge worked as intended, just not with precision
    • High idle - ~205 kPA (30 PSI)….not good
    • Idle – 29 kPa (4 PSI)….ouch
  • This is when I reviewed the part numbers in detail and found the difference for the tensioners. Obviously, I felt like a DA at this point
  • Still, I wanted to visually compare the old and new parts to check for obvious differences
    • I found pictures for the right-side tensioner (ML3Z-6L266-B), which looks nearly identical to the original part from the front side
    • However, I could not find a picture of the left-side tensioner (ML3Z-6L266-A)
  • Before digging back into the engine, we also wanted to validate the oil pressure. So, I purchased a mechanical gauge. For awareness....a M12x1.5 adapter fits the block
    • FORSCAN had been spot on and matched the mechanical gauge for high idle (30 PSI)
    • Idle indicated approximately 8 PSI on the mechanical gauge, but I attribute this to low accuracy below 10 PSI (the scale is 0-140 PSI)
    • I believe the 4 PSI indicated on FORSCAN was correct, and is lower than the 7 PSI trigger point for the low oil pressure warning indicator
Image


Image

  • Long story slightly shorter
    • Ordered up the correct tensioner part numbers and replaced them
    • Checked oil pressure with FORSCAN
      • High idle – 60+ PSI (gradually decreases as the engine warms up)
      • Idle – 23 PSI
  • So far there has been no damage indicated from the low oil pressure….so far
  • Tensioner Inspection - visually there is small difference in the right-side tensioner and a huge difference in the left-side tensioner. The correct Gen2 parts are at the top in the pictures
    • Note the slightly larger oil passage opening on the 2021+ right-side tensioner
    • Note the huge difference in the 2021+ left-side tensioner. When installed on a Gen2 block that large cavity is not sealed off. Hence the low oil pressure
Image


Image


I hope this helps someone avoid this problem.

Best!
Scott
 
#2 ·
Excellent post! Thank you!

One thing about this forum is that your post will ABSOLUTELY make a difference for someone(s). (The head librarian is legendary at information recall)

Really happy to hear that you caught it fast, and that the coldstart HighPressure stage IS enough, with the ill fitting parts, to get some oil where it most needs to be.
 
#3 ·
Wow, good digging. I hope you get a long life out of your truck because you more than deserve it!
 
#4 ·
@Scottr22 - thank you for the detailed post!
I’ve bookmarked this (as any good librarian should). Also, I’ll send you a PM with an offer to mail you a couple of our F150Ecoboost decals as a small token of appreciation.
 
F
#6 · (Edited)
Hi Scott - great to have you here! For the record, you’re absolutely correct the gen 3 left timing chain tensioner ML3Z-6L266-A does not fit a gen 2 engine because it creates an internal oil pressure leak. This can be catastrophic if not resolved

The RHS gen 3 tensioner ML3Z-6L266-B does fit and is an upgrade. FYI these are the gen 3 parts that will fit a gen 2 and upgrade your timing assembly:

Image


Gen3 Right Timing Chain Tensioner: ML3Z-6L266-B

Gen3 Metal Tensioner Arm - Driver's Side (LH): ML3Z-6K255-A

Gen3 Metal Tensioner Arm - Passenger Side (RH): ML3Z-6K255-B


Ive been meaning to cut open the HL3Z and ML3z tensioners to show everyone the differences. if you have an old worn out HL3Z tensioner and a new ML3Z tensioner available lmk, I’d love to use them to cut up for science
 
S
#7 ·
full-race geoff said:
if you have an old worn out HL3Z tensioner and a new ML3Z tensioner available lmk, I’d love to use them to cut up for science
Click to expand...
Geoff.....absolutely, happy to contribute! Want me to send to your attention at the F-R HQ address in Phoenix?

I agree and was not very concerned about the right-side tensioner, so it's good to know it's an upgrade. That said; I think I will pass on the installation right now. I've had my fill of seeing the full length of the timing chains for a while. LoL
 
F
#9 · (Edited)
Thanks a lot @Scottr22 for sending these parts over to me. They were delivered yesterday and I couldn’t wait to tear into them. Below is a photo of each tensioner, exploded view:


Gen 2 RHS:
Image

  • Retaining clip (Compress to remove)
  • Ball bearing check valve
  • Stiff, short, tensioner spring
  • Metal valve seat with plastic oil distribution cap


Gen 2 LHS:
Image


  • Retaining clip (Compress to remove)
  • Ball bearing check valve
  • Stiff, long, tensioner spring
  • Plastic valve seat / distribution cap


Gen 3 RHS:
Image

  • Retaining clip (expand to remove)
  • Actual machined valve seat check valve
  • Softer, mid length, tensioner spring
  • Metal valve seat with plastic oil distribution cap

Gen 3 LHS:
Image

  • Retaining clip (expand to remove)
  • Actual machined valve seat check valve
  • Softer, mid length, tensioner spring
  • Metal valve seat with plastic oil distribution cap
  • *internals are identical to gen3 RHS



Opinions to follow in the next post, need a day or so to put some cohesive thoughts together
 

Attachments

F
#10 · (Edited)
RHS tensioners are externally similar and physically interchangeable between Gen 2 and Gen 3 engines. Internally they are also somewhat similar. LHS gen 2 are the tensioner that’s substantially different. my opinions as a non engine builder:

Gen 3 gets a higher retention clip (right) compared to the Gen 2 (left). It can not be overstated how much more "tenacious" this type of clip appears to bite into the surface. it does not want to let go like the gen 2!
Image



Gen 3 RH (top) uses a larger “port” as cast, allowing more oil entering into the tensioner. (smaller gen 2 drilled on bottom)
Image



And this is mirrored on the LHS
Image



Looking at the tensioner pistons - they are all virtually identical, except the Gen 2 RH (far right) which has the smallest orifice and lets the least amount of oil to exit. The gen 2 LH pistons appears the same as both sides gen 3 tensioner pistons

Image



The Gen 2 springs are stiffer spring rate than Gen 3. I will test at headgames spring checker to get a rate. Ford uses this higher spring rate and longest length in the gen 2 LHS, shown on top:
Image


Gen 3 are on bottom. These are the same spring from LHS to RHS
 
F
#11 · (Edited)
The check valves that sit in the bore are different. Gen 2 uses a ball and seat. Gen 3 has a more elegant poppet valve design
Image



The backside of the check valve is also different. A gen 2 has a spring seat integrated with 3 ports for the oil. Whereas gen 3 has a tulip shaped exit for the oil to flow with less turbulence into the tensioner piston
Image




Next take a look at the piston side valve seat/ oil slinger. Metal (steel) RHS gen 2 appears to be the same as both side Gen 3. But it is plastic on the LHS Gen 2!! Why would such an important and high cycle part be plastic I do not know.
Image




And here is the reason the gen 3 LHS tensioner will not fit the gen 2, the bolts line up but there is a massive gasket overhang / internal oil leak:
Image



Maybe some enterprising engine builder will solve these dilemmas
 
S
#12 ·
Geoff....that is excellent documentation and photography. Nice work sir!

I hope that at some point, someone can add photos of Gen 2 and 3 blocks, specifically where the LH tensioner mounts. I think this would complement your excellent efforts to document the tensioners. I made a bad assumption in assuming the Gen 3 LH tensioner would seal without studying the block. Hindsight is 20/20!

Thanks,
Scott
 
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