2018 GT Engine tapping at 504miles

[chrishammondx]

I'm thinking out loud, but I'd bet, just like the guy who had the engine come apart, I bet during the spray-in cylinder wall process it was possible to get contamination/debris on assembly. I'd think this could result in some engines having cylinder wall scoring.

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[Kevin08]

can you post a video of it please? or listen mine to compare, are they similar?

Mine sounds basically identical to yours on cold starts. Doesn't do it on warm starts. I also want to say it's less noticeable after I changed my oil but I'll have to consciously check it to verify.

 

[gmupatriot]

can you post a video of it please? or listen mine to compare, are they similar?

My Gt with 12500 miles makes this noise on cold startup. Its a little less loud compared to yours but it is there. Once I drive off with the windows down, I can hear it with the RPMs going up but goes away within 2-3 minutes after startup.

The car doesnt burn any oil or seems to be down on power (if it is, I have no way of knowing cause it hauls ass so far) and like I said, once warm I just hear the normal engine sound (idle or reving)

 

[Silver Bullitt]

Dec 2017

Have you noticed any oil consumption? Mine's down a little over a 1/2 QT in 1500 miles. Taking it in for free oil change at 2000. Been ticking since about 250 miles.

 

[sigintel]

No oil consumption issue yet but still less than 1000 miles.
Checked oil at dealership at it was perfect cold mid hashmarks.

Update on the piston rocking noise:
I was told the bore offset in the coyote may need to be adjusted by 3-9mm.
Depending on which side of crank the rod is on, there is higher drag one side versus other during stroke resulting in rotational momentum carrying piston too far during transition where it grazes cylinder wall resulting in knock sound.
Supposedly this can be helped with asymmetrical pistons, increased ring spacing and bore offset.
I might have some of that wrong from second hand comments of my issue. Caveat emptor.

 

[IronG]

No oil consumption issue yet but still less than 1000 miles.
Checked oil at dealership at it was perfect cold mid hashmarks.

Update on the piston rocking noise:
I was told the bore offset in the coyote may need to be adjusted by 3-9mm.
Depending on which side of crank the rod is on, there is higher drag one side versus other during stroke resulting in rotational momentum carrying piston too far during transition where it grazes cylinder wall resulting in knock sound.
Supposedly this can be helped with asymmetrical pistons, increased ring spacing and bore offset.
I might have some of that wrong from translation since this was from friend of a friend and original email was in Japanese from a Mustang fan that works on Honda motors. Caveat emptor.

How exactly is your friend coming to that conclusion? Has he taken apart a Coyote engine and saw this or is he just guessing? I have done my fair share of engine rebuilds (just for kicks) and not sure how he or anyone without specific knowledge of the engine and one (or some) engines with an issue could know this. I am hoping he is just spit balling and trying to make you happy?

I have read a lot of posts speculating what or if the noise being heard is a problem or not. No facts that point to a systemic problem. Sure there will be issues with any mass produce mechanical device, car or otherwise, but to say or think that it is widespread is just darn silly. I will be ordering a GT soon and have absolutely no worry about a few engines having issues. I have no idea how those engines were treated during break in or in general. If they were modded in anyway etc. Not saying you did anything to promote an issue (if what you have is one) or not, but I think you really should wait for Ford to diagnose it and provide a fix if needed. If nothing else, think of as self preservation. I really hope your car is not damaged (or a lemon) and if it defective it is taken care of properly by Ford.

In all due respect you and anyone else who thinks they have an issue without any empirical proof that it is catastrophic should just avoid forums like these. It really does not help and could dissuade someone from getting a car that they would have enjoyed, but were scared off unnecessarily. If in the end it turns out to be a real issue for more than just a few statistically doomed from the start, and you can show what happened and why it happened, please come back and report in. I will be the first one to say oops. Just enjoy your car and if it does go south, just get it repaired and move on. Anyway, that's my nickel's worth on this subject.

 

[Ace21]

No oil consumption issue yet but still less than 1000 miles.
Checked oil at dealership at it was perfect cold mid hashmarks.

Update on the piston rocking noise:
I was told the bore offset in the coyote may need to be adjusted by 3-9mm.
Depending on which side of crank the rod is on, there is higher drag one side versus other during stroke resulting in rotational momentum carrying piston too far during transition where it grazes cylinder wall resulting in knock sound.
Supposedly this can be helped with asymmetrical pistons, increased ring spacing and bore offset.
I might have some of that wrong from translation since this was from friend of a friend and original email was in Japanese from a Mustang fan that works on Honda motors. Caveat emptor.

There should not be any issue with higher drag like stated above on a cross-plane crank with properly sized pistons, rings, and correct bore shape. The type of instance that the friend is describing is something that I have never seen, or heard of for any cross-plane crank V-8 as the inherited balance keeps side loading almost as minimal as a vertical I-6. Also if you were having such an issue you would be consuming oil in an accelerated volume as well as noticeable power loss because the bore would become more misshapen.

One last thing, cast hypereutectic pistons should not cold piston slap. If you are for sure experiencing cold piston slap, then there is most definitely an issue with the bore, piston/ring sizing, or bore liner. Cold piston slap is something that is only normal with forged pistons as their internal lattice structure is more compact making them experience more thermal expansion. The nature of cast hypereutectic pistons makes them have a lower coefficient of thermal expansion due to a less dense lattice structure and the silicon mixture.

With all that said, I have not seen anyone report whether the Gen 3 Coyote has cast hypereutectic pistons or forged.... they could be pulling a 1991/92 5L factory forged piston instance again!!

 

[sigintel]

How exactly is your friend coming to that conclusion? Has he taken apart a Coyote engine and saw this or is he just guessing?
## I will ask. These guys arent emailing in english so its not like I can ask directly. Theres also a time zone difference and these arent Ford engineers. Our shared background is having worked specifically on NVH issues in drivelines all the way from tires to engines. Please reread my last post, it does not say there is a “problem”, simply that there are some variables that an experienced engineer suggest I try changing in any possible build. ##

I have done my fair share of engine rebuilds (just for kicks) and not sure how he or anyone without specific knowledge of the engine and one (or some) engines with an issue could know this. I am hoping he is just spit balling and trying to make you happy?
## I am sure he wants me to be happy. ##

I have read a lot of posts speculating what or if the noise being heard is a problem or not. No facts that point to a systemic problem. Sure there will be issues with any mass produce mechanical device, car or otherwise, but to say or think that it is widespread is just darn silly. I will be ordering a GT soon and have absolutely no worry about a few engines having issues. I have no idea how those engines were treated during break in or in general. If they were modded in anyway etc. Not saying you did anything to promote an issue (if what you have is one) or not, but I think you really should wait for Ford to diagnose it and provide a fix if needed. If nothing else, think of as self preservation. I really hope your car is not damaged (or a lemon) and if it defective it is taken care of properly by Ford.

##I am under the impression that this is more of an NVH issue (Noise Vibration Harshness). It may actually go away over time. It is unknown what affect it may have on compression, oil use, ring wear, cylinder wear, piston/ring drag/friction, etc.
I will scope the bore, check compression, watch oil use, note any change depending on oil type/viscosity/temperature.

In all due respect you and anyone else who thinks they have an issue without any empirical proof that it is catastrophic should just avoid forums like these.
## whoa! I dont think it’s catastrophic the more I learn. I think its specifically an NVH issue.

It really does not help and could dissuade someone from getting a car that they would have enjoyed, but were scared off unnecessarily.
## Totally agree! It should not scare people off. I am after a solid explanation of what it is and would prefer to get that from FORD, but havent heard any good explanations yet other than TSB for GT350 about the bbq/typewriter click. I think its same thing now that coyote has voodoo liner.

If in the end it turns out to be a real issue for more than just a few statistically doomed from the start, and you can show what happened and why it happened, please come back and report in. I will be the first one to say oops. Just enjoy your car and if it does go south, just get it repaired and move on. Anyway, that's my nickel's worth on this subject.

## Input appreciated! I plan to enjoy the car to its fullest (and then some). At the same time, I would love to understand exactly whats causing it. I had never heard about bore offset before that email. I assumed all bores were centered on crank axis.
That is not the case.

 

[sigintel]

There should not be any issue with higher drag like stated above on a cross-plane crank with properly sized pistons, rings, and correct bore shape. The type of instance that the friend is describing is something that I have never seen, or heard of for any cross-plane crank V-8 as the inherited balance keeps side loading almost as minimal as a vertical I-6.
##”almost” - super slick spray in liner is less aligning drag in bore. Less differential in drag needed to slightly float piston aware from perfectly square in bore.

Also if you were having such an issue you would be consuming oil in an accelerated volume as well as noticeable power loss because the bore would become more misshapen.
## nah, not for very light amounts of transition of piston angle.

One last thing, cast hypereutectic pistons should not cold piston slap. If you are for sure experiencing cold piston slap, then there is most definitely an issue with the bore, piston/ring sizing, or bore liner. Cold piston slap is something that is only normal with forged pistons as their internal lattice structure is more compact making them experience more thermal expansion. The nature of cast hypereutectic pistons makes them have a lower coefficient of thermal expansion due to a less dense lattice structure and the silicon mixture.
## not sure if cold piston slap. It does go away as the engine warms up. I expect it to decrease when changing to QSUD full syn (prolly try 5w30 or 5w20).

With all that said, I have not seen anyone report whether the Gen 3 Coyote has cast hypereutectic pistons or forged.... they could be pulling a 1991/92 5L factory forged piston instance again!!

 

[sigintel]

Oh man. This stuff gets pretty technical, not sure if its fun to read.

https://www.fev.com/fileadmin/user_...pactonPistonAndPistonRingFrictionBehavior.pdf

https://www.google.com/search?q=bore+offset+piston+slap&ie=UTF-8&oe=UTF-8&hl=en-us&client=safari


Beyond cold piston slap: the thrust bearing lash on the crank can also be checked w dial guage on end of crank damper.

Theory:
If the crank floats too much fore or aft, the cylinders will show “loading” marks on fore/aft walls of a cylinder.
If skirt drags in excess rocking, marks will more likely be transverse (90 deg off from fore/aft).

 

[Ace21]

Bore offset is present in engines called desaxe engines, however, all modern desaxe engines use an offer positioned with the rotation of the crank giving better leverage to the crank during each cylinders' cycles while eliminating sidewall thrust.

The second post is absolutely a thing, but it would have to be a serious error on the assemblers part, as well as the computers because I believe all of the bearings are measured for consistency and tolerance before selection. Not impossible, but in today's newer computerized check step style assemblies it is hard to override forced measurements.

 

[sigintel]

Update: motor still in one piece. Will try n borescope if I can ever get it back.
#neverloantools

 

[Elp_jc]

Yeah, most of those abnormal noises are 'normal'. Ha ha. They shouldn't be there, but most are not detrimental to the engine. A result of relaxed tolerances and/or cheaper parts/processes, to save money... but everybody is doing that nowadays.

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