Ford Timing Chain Tensioner Cutaway

[Fix4Dirt]

Hi All,

So I installed the two external tensioners this weekend. Cold start up rattle is significantly improved, although it can still be heard for a split second. The rattle at 2100 to 2300 RPM is quieter but is still present. And it did take about 15 miles of driving to quiet down. Just a couple of observations to add to the "knowledge base" in this thread. The old tensioners had no crush washers from the factory. I am not saying they should have, it just surprised me.

Also after I started using the WOT starts the car threw a fuel rail sensor code. With the new tensioners and no WOT starts the code has gone away. I do not know for sure they were related but the code only came up after the WOT starts and went away after several driving cycles with no WOT.

In this or a related thread someone pointed out the car might go 10 miles or it might go 50 thousand before the internal chain and guides totally fail. At this point other than the engine the Explorer is in very good condition (and I really like it) so I will start saving up for the expense of having the engine pulled and the internals replaced. Which bring me to wanting the opinion of the group. Should I look at the expense of having a remanufactured engine installed? My initial plan before this issue was to turn the Explorer into a second car in about two years and that is what I would still like to do. With the cost of used cars right now I think my best bet is to have the Explorer repaired but I want to make sure I know my options and what each will cost.

personally, depending on age etc, if youre going thru the work of pulling the engine, replacing the timing components is good, but you may as well get a remanned unit, as it should last for many more years... personally, ive been quoted about 4k to do front and resr timing guides, but installing a remanned one afaik was around 6-7k, but I get alot of new parts in this deal, so if I werent thinking about going v8, i wouldve gone down this route... hope this helps!

 

[donalds]

Remain Engine cost me , 2500 + 600 for core which I got back when the old engine was returned
250 for shipping all included
Just my experience
Good luck

 

[CDW6212R]

I serviced my 99 SOHC in 2006 with 77,450 miles, pictured in my project link below. The cost then was about $65 for the front cassette, Ford only parts, $80 or so for both external tensioners, $160 for the tool kit, and around $100 for the other front tensioners and main chain etc. The labor is the biggest part of it, and if the rear cassette is known or suspected damaged, then pulling the engine is required.

So the job can be done in a reasonable time by a good shop if you have the special tool kit in hand. I'd call it 6-8 hours for a good mechanic, for everything except the rear cassette. I didn't do the rear when I first went at mine after buying it. The trans died after 153k miles, so it's time to do the service work again for my SOHC. It has had no odd noises, but I went at it first thing, and this time I'll do the rear cassette also.

The shortblock of the 4.0 is extremely reliable, just like the 302 is. If the engine hasn't been hurt by the timing chain system, there should be no need to replace the shortblock. The heads are very good also if the oil has been changed regularly with great oil(synthetic, not others), and not hurt by the timing system. The plastic guides of those cassettes will eventually come apart in pieces, and they can get into the oil passages sometimes.

If you suspect any guide damage, remove both oil pans, and then the oil pump pickup. Inspect that carefully and see if there's any debris in it at all. Most pickups have a way for some small objects to get around the screen. Mine was clear, but I replaced the pump anyway, which is expensive for this engine.

 

[94Eddie]

In this or a related thread someone pointed out the car might go 10 miles or it might go 50 thousand before the internal chain and guides totally fail. At this point other than the engine the Explorer is in very good condition (and I really like it) so I will start saving up for the expense of having the engine pulled and the internals replaced. Which bring me to wanting the opinion of the group. Should I look at the expense of having a remanufactured engine installed? My initial plan before this issue was to turn the Explorer into a second car in about two years and that is what I would still like to do. With the cost of used cars right now I think my best bet is to have the Explorer repaired but I want to make sure I know my options and what each will cost.

Since you live in New Mexico I think spending a good amount of money on the engine and/or transmission is justified if the chassis is solid and the vehicle is in good shape overall. If you lived in the upper Midwest or in the Northeast then I wouldn't recommend this. Where you live rust is a non issue which keeps a vehicle viable for much, much longer periods of time compared to other areas where roads are heavily salted.

 

[chris8428]

personally, depending on age etc, if youre going thru the work of pulling the engine, replacing the timing components is good, but you may as well get a remanned unit, as it should last for many more years... personally, ive been quoted about 4k to do front and resr timing guides, but installing a remanned one afaik was around 6-7k, but I get alot of new parts in this deal, so if I werent thinking about going v8, i wouldve gone down this route... hope this helps!

Thanks for the information. And those numbers are in the ballpark of what I was quoted.

 

[Justin J]

This is very helpful, Donald!

Do you know why the front piston needs a small hole? What if it’s blocked?

 

[donalds]

This is very helpful, Donald!

Do you know why the front piston needs a small hole? What if it’s blocked?

I think its their to allow air to get out
What if its blocked that's why oil changes are king on this engine

 

[Justin J]

Donald, so when it’s normal, oil presses on the rubber piston (the one with a one-way valve), which further presses on the spring that transfers the additional force to the SS piston. Right? If this were the case, I think the tiny hole would be for air normally.

 

[donalds]

The whole thing fills with oil
The valve just only lets oil in
The little hole at the end is where it goes out
Notice how the input hole is bigger so pressure builds up extending the tensioner
Maybe someone can explain better than I can

 

[Justin J]

This article helps, though it describes a different design: How a Hydraulic Tensioner Works

Now I think Ford had cheaped its design by using a rubber piston.

 

[donalds]

This article helps, though it describes a different design: How a Hydraulic Tensioner Works

Now I think Ford had cheaped its design by using a rubber piston.

There's no rubber piston just a stainless steel plunger
The little rubber disk is a seal / one way valve that's it

 

[410Fortune]

Can’t believe I never saw this till now

It’s simple sohc engine must have full synthetic and must have clean oil all the time!!
Sohc engine I would change oil at 3-5000 religiously and they will last forever.. same is true for most engines, except with these tensioners in there it is an absolute must. We have seen the difference inside the engines and we have sohcs on this forum that have well over 300k on them… I have never seen a sohc engine fail due to a lower end issue they all get scrapped way before there time simply because of lack of maintenance

I think I remember ford recommends the tensioners are changes at 90-120k miles?? Something like this. Not sure anyone ever actually changes them unless they are here on ef and know what is up.

Long live the manual tensioners!! No need to wait for oil pressure or hope the rubber valve doesn’t dry up… it’s manually adjusted once and forget about it

 

[Justin J]

There is another way for the Ford one to work: the chamber where the spring sits is full of high pressure oil when the engine is running. The tiny hole allows oil to gradually go out when the chain pressure change is needed based on engine speed or load level.

If this were the case:

1. when the hole were blocked and the check valve were ok, the tensioner would work as a steel block;
2. When the hole were not blocked but the check valve were bad (aka leaking), the tensioner won’t build up enough pressure; only the spring works.

One question is, the spring is designed to help when engine starts and oil pressure is low. In case 2, we should not expect to hear any rattling noise, UNLESS the spring becomes fatigued. Does the spring fatigue easily? I still doubt it!

There's no rubber piston just a stainless steel plunger
The little rubber disk is a seal / one way valve that's it

 

[410Fortune]

If the spring does not get weak over time how do you explain the cold rattle start happening after 150k miles to most sohc engines?
Wear on the guides? Chains stretching?
Oil pressure takes a minute to build up in the heads. The spring seems to work great when low miles…. Then the rattle comes
The oil pumps are bomb proof
It has to be the springs!
Show me a spring in a car that does not fatigue over time

 

[Justin J]

Long live the manual tensioners!! No need to wait for oil pressure or hope the rubber valve doesn’t dry up… it’s manually adjusted once and forget about it

Sorry, what manual tensioners do you refer to please?

 

[Fix4Dirt]

Sorry, what manual tensioners do you refer to please?

they fit polaris rzrs iirc, heres a lnk

13-16 Polaris Ranger 900 xp 1000 cnc Manual Cam Timing Chain Tensioner | eBay

POLARIS RANGER 1000 XP--2015-16. pOLARIS RANGER 900 MODELS --2013-16.

www.ebay.com

RZR manual Tensioner

Will this replacement manual tensioner fit my '97 4.0 SOHC? It is the cheapest that I have seen them yet. Stainless Cam Timing Chain Tensioner Manual Gasket For Polaris RZR 570 XP 900 S1 | eBay

www.explorerforum.com

 

[Justin J]

If the spring does not get weak over time how do you explain the cold rattle start happening after 150k miles to most sohc engines?
Wear on the guides? Chains stretching?
Oil pressure takes a minute to build up in the heads. The spring seems to work great when low miles…. Then the rattle comes
The oil pumps are bomb proof
It has to be the springs!
Show me a spring in a car that does not fatigue over time

I’m still trying to figure out how it works, especially when it fails.

Based on some YouTube videos in which some people tried to prime these tensioners, it seems the tiny hole in the SS piston normally doesn’t let oil out at all, and the tensioners get super stiff after being primed. People had to use a bench vise to make it to retract, which could possibly damage the tensioners; in addition, it means pre-priming these tensioners before installation is TOTALLY WRONG!

If my understanding above were true, it means the spring in these tensioners doesn’t help much AFTER BEING PRIMED. THE SPING ONLY HELPS FOR THE VERY FIRST TIME BEFORE THEY ARE PRIMED/FILLED WITH OIL, OR WHEN THE SEALS FAIL, since normally the oil will stay inside and maintain the pressure and tension, even after engine off or overnight and so on.

Now I think the tensioner failure could be twofold: either the rubber with one-way valve, as shown in Donald’s video, OR the seal for the front hole in the SS piston.

To explain the noise after the tensioner fails (either seal), because the tensioner can’t maintain its INSIDE OIL PRESSURE anymore. The spring itself is NOT ENOUGH to eliminate the rattling and noise, even the tensioner is brand new, it just helps a little bit in these two scenarios. so when it’s failed, it behaves exactly like the VERY FIRST TIME after a tensioner is installed (w/o pre-priming). Actually this has been verified by this guy in this video.

 

[Fix4Dirt]

iirc, and i dont rememebr very weel, but i think the spring is there to maintain some tension on startup, hence the "statup rattle" as the springs weaken with age the tension on startup is no longer there, but as the oil pressure builds it goes away.. and i think i left my old tensiner out with oil still in and the next day it was back to squishy sponge... but i dont emember too well

 

[Justin J]

iirc, and i dont rememebr very weel, but i think the spring is there to maintain some tension on startup, hence the "statup rattle" as the springs weaken with age the tension on startup is no longer there, but as the oil pressure builds it goes away.. and i think i left my old tensiner out with oil still in and the next day it was back to squishy sponge... but i dont emember too well

Do you hear the startup rattle in the above video when he starts his car the first time after he installed a new tensioner? THE SPRING IS NOT ENOUGH! So I won’t blame spring fatigue on this. It’s just designed so.

 

[donalds]

The spring does a few things one is to keeping consistent pressure on the piston so the one way valve works