Mustang GT350 Forums banner

1 - 20 of 101 Posts

·
Registered
Joined
·
30 Posts
Discussion Starter · #1 ·
All,

When the engine is cold, my car has a pronounced valvetrain 'rattle' around 2,000 rpm. It's not consistent, and comes and goes multiple times if you hold the revs between 2,000 and 2,500. It reminds me of how the hydraulic lifters in my older cars sounded when they were starved for oil. By 2,500 rpm it seems to be gone, but the noise is very pronounced at 2,000 rpm, and brings back bad memories about good engines starving for oil. Anyone else experiencing this? Is it possibly caused by some change in cam timing or other normal function of the valvetrain? (I checked the oil and it was fine by the way, so low oil isn't the culprit.) The insight of the group is welcome. Thanks,

Hawkeye
 

·
Registered
Joined
·
232 Posts
All,

When the engine is cold, my car has a pronounced valvetrain 'rattle' around 2,000 rpm. It's not consistent, and comes and goes multiple times if you hold the revs between 2,000 and 2,500. It reminds me of how the hydraulic lifters in my older cars sounded when they were starved for oil. By 2,500 rpm it seems to be gone, but the noise is very pronounced at 2,000 rpm, and brings back bad memories about good engines starving for oil. Anyone else experiencing this? Is it possibly caused by some change in cam timing or other normal function of the valvetrain? (I checked the oil and it was fine by the way, so low oil isn't the culprit.) The insight of the group is welcome. Thanks,

Hawkeye
Hello Hawkeye,
I haven't experienced this rattling noise... Are you able to open up your hood to try and pinpoint it better while someone revs it to 2000-2500? First make sure your oil pressure is adequate - I would say at least 50 psi or so when cold. Have you checked your oil level again? (I'd do it every time I started it until the rattle is diagnosed...) I'd be wary of going beyond idle while the rattle is there and/or your oil pressure is low until you get a better sense of what it is. Sometimes brackets, harnesses come loose and rattle....I have not heard of cam adjustments or timing changes needed for the Voodoo....Kind of basic stuff and not meaning to insult, just trying to think of what I would do if I did hear the rattle in my car....Good Luck!!
 

·
Registered
Joined
·
30 Posts
Discussion Starter · #3 ·
Tankman,

Thanks for the response. Good idea to have someone else rev the motor while I try to localize the noise under the hood. I'll do that tomorrow. As far as oil pressure and oil level, both are fine. (Pressure >50 psi and level 'full'.) If I can't find the noise, I'll take it to the local dealer for a look. Thanks again.
 

·
Registered
Joined
·
232 Posts
Tankman,

Thanks for the response. Good idea to have someone else rev the motor while I try to localize the noise under the hood. I'll do that tomorrow. As far as oil pressure and oil level, both are fine. (Pressure >50 psi and level 'full'.) If I can't find the noise, I'll take it to the local dealer for a look. Thanks again.
You bet Hawkeye! Sounds like a plan! Good Luck!!
 

·
Registered
Joined
·
30 Posts
Discussion Starter · #5 ·
Drove the car tonight and understand it better, but still don't have 'the answer'. Along with the engine being cold, the noise arises when the throttle is barely open, just enough to hold the car steady or accelerate very slowly. Press the throttle any deeper and the noise goes away. Let off the throttle completely, and it goes away. You only hear it at 'barely open', and it's much less prominent when the engine is warm. I notice it most when I first start up and drive out of my neighborhood. The speed limit is 25, so I'm easing along in 2nd or 3rd with just enough throttle to hold speed. In those conditions the rattle is very prominent, and sounds like a bad lifter. However, once I'm out of the 'hood' and push the pedal down, the rattle is gone, and the roar begins. If nobody else on the forum is seeing this, I'll take it to the local dealer later this week and ask then to take a look. Thanks.
 

·
Registered
Joined
·
232 Posts
I'll take it to the local dealer later this week and ask then to take a look. Thanks.
Thanks for the additional info. I'll post if I ever have a similar sound...Seems like a prudent plan to have the dealer check it out. Please let us know the outcome and good luck!
 

·
Registered
Joined
·
17 Posts
Hawkeye, I know you are around the Atl, but what area, I ask because I live on the west side and although I am still upset about you bringing my double back to the area (kidding), I am willing to help you out with your car or anything like that if you wanted to stop by, I would at least get some insight on the sound before going to the dealer, nothing against dealers, I know some good people at some, but I would not just trust in any tech at a dealer to diagnose or fix my car. Anyway, I am here to help if you would like, I know several dealers, and also some of the best Ford people around here, and have been around a shop or two before, just thought I would try and help, let me know, I hope you have a great day and everything works out with the noise.
 

·
Registered
Joined
·
76 Posts
Have you changed the oil yet? What weight oil is in it?

Two possible issues that show up on modular motors, but haven't heard of any other 5.2 doing it yet.

A cam phaser, will making a strong ticking noise. Like an old school lifter.
A timing chain will give you a rattling noise typically at cold start up only. This is usually due to a timing chain tensioner.

Either way, it should be under warranty
 

·
Registered
Joined
·
30 Posts
Discussion Starter · #10 ·
Have you changed the oil yet? What weight oil is in it?

Two possible issues that show up on modular motors, but haven't heard of any other 5.2 doing it yet.

A cam phaser, will making a strong ticking noise. Like an old school lifter.
A timing chain will give you a rattling noise typically at cold start up only. This is usually due to a timing chain tensioner.

Either way, it should be under warranty
The car has less than 2,000 miles on it, so the oil is still the original fill. Not sure what the stock oil viscosity is. Also, I took the car to the local dealer Thursday, and they heard the sound, but couldn't localize it. It only happens when the car is in motion, at low rpm (2,000 - 2,500). With the car at rest (clutch in or clutch out, in gear or not), it will not make the sound, so they can't just open the hood and listen for it. Several techs heard it from inside the cabin while the car was moving, but none of them were sure of the source. Rather than guess, they decided to call in one of Ford's Field Tech Engineers. He will be here next Friday. Hopefully he will have some idea about its cause. The dealership service manager says they are comfortable doing the repairs, if the root cause is not related to the engine itself. If it is coming from the engine, they'll rely on expertise from Ford.
 

·
Registered
Joined
·
30 Posts
Discussion Starter · #12 ·
Take a look at SSM 45738, Ford considers that normal operation.
That is an awesome find, and describes the sound and conditions almost perfectly. You must have access to the Ford bulletin system, and it must be restricted, since a Google search on SSM 45738 came up empty. Thanks for taking the time to find it. I'll forward it to the Service Manager at the local dealer. Way back in the day, I built a 350 for an old Z28 (1970 model). The wrist pins were termed 'free floating' and they 'clacked' until the motor was warm. Sounded like a diesel for the first few minutes. This sounds like a similar issue, though the sound is higher pitched than what I remember. Thanks again for taking the time to research this and send it on.

Hawkeye
 

·
Registered
Joined
·
76 Posts
Very interesting find. The only problem I have is that these pistons are not traditional forged pistons that you would typically have piston slap from. They are hypereutectic pistons and in an aluminum block.
Typically piston slap comes from a loose piston. When running a true forged piston in an iron block you want to run loose sidewall clearance so that the piston has room to expand as it reaches operating temp.
A hypereutectic piston in an aluminum block does not need room to expand. So, I have to call B.S. on their statement. If you look at our pistons they have a very short skirt. They do have a skirt coating.
The ones I pulled out at 500 miles have zero wear on the coating. I think they are on the right track but is more in the geometry of the flat crank, short skirt pistons that don't have offset wrist pins.
Shame on Ford for once again confusing their "forged" pistons and rods with real forged units. Just because their process for manufacturing is technically a forging process... they are not forged units!
 

·
Registered
Joined
·
3 Posts
My GT350 has the same issue. Once the engine is fully wormed up, the sound disappears.
With 40 years of engine building experience, I can emphatically state that this is a common issue with flat plane cranks, "forged pistons", short piston skirts and no offset wrist pins.
It doesn't bother me in the least and I chalk this all up to having a high-revving engine with high specific output.

Regarding forging, there is no legal definition. Forging comes from the latin word "to hammer", so technically there are no forged pistons. Ford's high pressure piston castings with high silicon content are very stable at high temperature.
They can also be assembled with tight tolerances.
Classically designed forged pistons are much stronger, but also heavier, and require higher cylinder clearances. This presents major problems for OEMs because of the "Cold 505" emissions test cycle included in the EPA's FTP-72 regulations.
The extra forged piston clearance can contribute to slightly higher exhaust emissions at startup. The EPA doesn't care that the problem is resolved when the engine warms up, so Ford has to design around the rule book.
However, Ford was trying to wring the last possible HP from this engine for obvious reasons.
Engines that have 12:1 compression and are revving at 8000+ rpm also reduce the available time for cooling. Ford even incorporated jets to spray oil on the underside of the pistons for additional cooling.
Like all factory engines, the new 5.2 is a compromise. But what a gem it is!
 

·
Registered
Joined
·
30 Posts
Discussion Starter · #15 ·
A Ford Field Service Engineer drove the car last Friday morning. The car 'stayed the night' inside the dealership so he was able to listen to it upon cold start. He thought the noise matched the description in the field service bulletin, and contacted two other FSEs who agreed. One of the other FSEs had multiple exposures to the noise, and said that one GT350 owner received two new engines before they determined that the noise was 'normal' for this car. I hadn't heard this, and found it interesting enough to pass on.

That said, it's back at the garage today for two reasons:

1) They're investigating another possible source for the noise: An aluminum plate that might be vibrating against a heat shield. I don't know the name of the plate, or its exact location, but replacing it would require removal of the transmission. I think this is a stretch, but the car was already in the shop for reason number 2.
2) Check engine light. I noticed it Sunday morning and couldn't get it to clear. Two days earlier I noticed that cylinder head temperature had dropped to 170 degrees, about 30 degrees lower than normal. Lower engine temps don't sound like a bad thing, but it was odd. (I'd been at the drag strip that night, and the car ran stronger on every pass. Trap speed for the first run was 114 mph, but on the last run it was 118. I wonder if the falling cylinder head temps made any difference?...) Apparently the car's computer didn't like it and threw the code. The dealership is replacing both the thermostat and sensor, and I hope to have it back tomorrow.
 

·
Registered
Joined
·
76 Posts
A Ford Field Service Engineer drove the car last Friday morning. The car 'stayed the night' inside the dealership so he was able to listen to it upon cold start. He thought the noise matched the description in the field service bulletin, and contacted two other FSEs who agreed. One of the other FSEs had multiple exposures to the noise, and said that one GT350 owner received two new engines before they determined that the noise was 'normal' for this car. I hadn't heard this, and found it interesting enough to pass on.

That said, it's back at the garage today for two reasons:

1) They're investigating another possible source for the noise: An aluminum plate that might be vibrating against a heat shield. I don't know the name of the plate, or its exact location, but replacing it would require removal of the transmission. I think this is a stretch, but the car was already in the shop for reason number 2.
2) Check engine light. I noticed it Sunday morning and couldn't get it to clear. Two days earlier I noticed that cylinder head temperature had dropped to 170 degrees, about 30 degrees lower than normal. Lower engine temps don't sound like a bad thing, but it was odd. (I'd been at the drag strip that night, and the car ran stronger on every pass. Trap speed for the first run was 114 mph, but on the last run it was 118. I wonder if the falling cylinder head temps made any difference?...) Apparently the car's computer didn't like it and threw the code. The dealership is replacing both the thermostat and sensor, and I hope to have it back tomorrow.

Don't tell them it was at the track. Voids all warranties
 

·
Registered
Joined
·
30 Posts
Discussion Starter · #18 ·
Got the car back this afternoon. I made no mention of the drag strip... They replaced the thermostat and cylinder head temp sensor, because they weren't sure ifthe temps were really low (thermostat) or just reading low (sensor). Indicated temp went from around 175 when I took it in, to around 215 on the way home. Outside air temps are roughly the same. I think the thermostat must have been stuck open, because oil temp also rose after the new thermostat was installed, going from around 185 before to around 210 today. Do those temps sound 'average' for your cars?

Also, they checked an aluminum plate in front of the trans to see if it was the source of the noise that I originally took the car in for. Final answer: 'No', the noise is the same one described in the service bulletin above, and is most likely coming from engine internals (pistons) when it's cold.

Hawkeye
 

·
Registered
Joined
·
9 Posts
This is an odd statement. During development, Ford must have dozens of these engines either on test stands or in cars and still they did not know that the noise was normal? Apparently not, as they replaced 2 engines on a customer's car? I don't get it.

I would hate to be this customer.

One of the other FSEs had multiple exposures to the noise, and said that one GT350 owner received two new engines before they determined that the noise was 'normal' for this car. I hadn't heard this, and found it interesting enough to pass on.
 

·
Registered
Joined
·
30 Posts
Discussion Starter · #20 ·
This is an odd statement. During development, Ford must have dozens of these engines either on test stands or in cars and still they did not know that the noise was normal? Apparently not, as they replaced 2 engines on a customer's car? I don't get it.

I would hate to be this customer.
I wonder if the testing regimen included much time with the car accelerating very slowly (gas pedal barely depressed) at 1,500 - 2,500 rpm on a cold engine. Those are the conditions needed to generate the noise. In any case, I agree that it's surprising they didn't identify it in advance, and I wouldn't want to be the guy driving on engine #3, or the service engineer who thought two engine replacements were appropriate...
 
1 - 20 of 101 Posts
Top