why the plastic guides on timing chain?

[imp]

@imp,

The OP wants to come up with a Nylon Roller to replace the slack side guide?

What do you think?

@shucker1
Gotta look into this to understand more. Offhand, Nylon hardens with temp. and long-term chemical exposure (what's in these synthetics, anyway? Teflon, maybe, depends on unit loading, teflon "cold-flows", meaning it cannot support compressive load long term even if less than yield stress. Maybe something with a needle bearing for rotational support. I dunno. imp

 

[imp]

Has anyone successfully designed, built, and tried out a gear-drive retro-fit for chains on these engines? This Cat engine designed for over the road truck use is Dual-overhead cammed, has a maze of gears up front, nary a single chain. Cat knew better, of course. I saw that engine pull rated HP on the dyno stand for weeks on end.


I'm listing what I know here, am open to correction where wrong, can't say "put a roller" here, or some other re-engineering foible, whatever we change will be unproven. I doubt the Germans threw it together without significant amounts of test time. Can we easily make it better?

The Germans in Cologne seem to have used their usual prowess on the 4.0 OHC with lots of chains, and some inaccessible, in Engineering which does get them well-through warranty, but hell with the owner after that, charge him blind to repair/replace. OTOH, not every single one can be said it will fail prematurely, as no one agrees when that is. I've got 165k, another guy has 200k, still quiet. Fixes have included build tensioner pressure quicker, store pressure in bladders, spin an oil pump when key ON at first, etc.

Has anyone replaced the tensioners with spring-loaded devices? Then on to the guides.....evidently early ones failed real often, so "better" guides were used after what, 2003? Metallic guides?

Looks to me like the camshafts are different, one side to the other. What about in the 4.6? Is the valve layout typical Ford EIEIEIEI on both heads, both identical, both turn in the same direction? If heads interchange, first valve up front is different one side to the other. That don't matter, as firing order can take care of that. Since cams for each cylinder are identically-timed for each cylinder, looks like both cams could be identical. But spring-loaded tensioners.

Hell, I don't even know what kind of chains these are. Having heard all my life how timing chains "stretch", and scratched my head many times as a teen-aged grease monkey, I think I understand chains a bit better now. Anyone who has done lots of chain-sawing (I did 20 cords each season in Missouri for 13 years) knows the damned chains are forever losing tension. They are side-linked and pinned. Say a timing chain has 100 links, and each hole has worn bigger by only 0.002", thickness of a human hair, entirely possible, the 100 link length has increased by 0.2", 2/10 of an inch, almost 1/4 inch. Pix look like 100 is too small a number. Think that don't affect timing? A roller-chain should wear less, I THINK, how much less, if so, I dunno. What about sprocket tooth wear?

GEARS are the only realistically-sound way to drive crankshaft-driven overhead camshafts, IMO. What about driving the camshafts directly with a stepping motor? Feasible? Has it ever been done? Could dynamically change timing while running.

Now y'all think I AM nuts! My wife KNOWS........
imp

 

[fast_dave]

@2000StreetRod
Your image is of an OHV camshaft drive chain? Why did it have a tensioner at all? Umpteen millions of Overhead Valve Engines have been built and used without any tensioner. If the idea was to decrease loss of "design valve timing" by tensioning the chain, as the links wear, the loss of timing accuracy presents itself anyway.

I don't understand something here, evidently. imp

@imp

Here's a pic of the actual FORD 4.0 OHV timing chain w/ tensioner and guide (my engine)

NOTE: The FORD 4.0 engine was designed and built in Cologne Germany. They began building them in the early 70's for the Mercury Capri, and at that time it started out as a 2.8

Little know fact - FORD Germany built & shipped assembled engines on a transport ship to FORD for distribution to Explorer assembly plants, and subsequent installation into Explorers.

Whatever compound the ORIGINAL EQUIPMENT (Brown Color) Tensioner and Guide are made out of, I have to say, there was ZERO wear on both of these parts where they make contact with the timing chain.

I've had my timing cover off twice, once at approx 150,000 and once at approx 200,000 and carefully inspected both times (knowing all of the problems with cassettes and guides in FORD SOHC engines).

My Ex's Tensioner and Guide are as smooth as smooth can be - they look factory new. BUT - I have to add the disclaimer that I always use either Mobil 1 or Pennzoil Platnium Full Synthetic Oil, and religiously change it AND the oil filter every 3,000 miles. Fluids, for all they do, are the cheapest insurance you put in your vehicle (as per my HS Auto Shop Teacher - back when there was such a thing).

With regards to the engineering of the 4.0 OHV timing chain assembly - you do not question "Zee Germans" as they believe they have a superior engineered method ;-)

 

[96eb96]

@imp

Here's a pic of the actual FORD 4.0 OHV timing chain w/ tensioner and guide (my engine)

NOTE: The FORD 4.0 engine was designed and built in Cologne Germany. They began building them in the early 70's for the Mercury Capri, and at that time it started out as a 2.8

Little know fact - FORD Germany built & shipped assembled engines on a transport ship to FORD for distribution to Explorer assembly plants, and subsequent installation into Explorers.

Whatever compound the ORIGINAL EQUIPMENT (Brown Color) Tensioner and Guide are made out of, I have to say, there was ZERO wear on both of these parts where they make contact with the timing chain.

I've had my timing cover off twice, once at approx 150,000 and once at approx 200,000 and carefully inspected both times (knowing all of the problems with cassettes and guides in FORD SOHC engines).

My Ex's Tensioner and Guide are as smooth as smooth can be - they look factory new. BUT - I have to add the disclaimer that I always use either Mobil 1 or Pennzoil Platnium Full Synthetic Oil, and religiously change it AND the oil filter every 3,000 miles. Fluids, for all they do, are the cheapest insurance you put in your vehicle (as per my HS Auto Shop Teacher - back when there was such a thing).

With regards to the engineering of the 4.0 OHV timing chain assembly - you do not question "Zee Germans" as they believe they have a superior engineered method ;-)

Victor Reinz was the part OEM for those engines. The ford HGs have their trademark. Those HGs never fail either. It is the heads that are the problem. Many of the gaskets too look identical to the OEM Ford parts. They were an old time supplier to BMW too, which then made indestructible engines. There is a cash for clunker vid on YT with the OHV running for 2 minutes with a ROD OUT THE BLOCK. If not for the weak heads(that could go a long time even cracked) those engines would literally be indestructible. They are fully cast iron (no aluminum). Try to search the forum for bottom end, valve, or timing failure. Good luck.

Crown Vic engines have plenty of plastic timing guides but you never hear of an issue before 300K(even more). I think some between 01-03 or so were silently recalled and replaced for a similar issue. And it is a very doable job, no rear chain BS. Funny that Audi moved their timing to the rear of the engine too, and had similar problems in their engines. Maybe it is a German thing.

I have a feeling lower quality was speced for those guides. There are different materials in the bin and cost is always king. Ford was certainly cutting cost on those Explorers. They even used weaker metal in the A and B pillars as the years went on. They were milking the profit cow until she died.

 

[Foz1359]

This one is an 05, one owner, 140k and the golden bronze mirror clean guts are tell tale of regular oil changes. No noise at startup, idle or driving. I thought $1700 was a great buy ...until I pulled that right pass side valve cover off. I'd bet many of these are rolling along with the exact same condition and the only indicator is when the vc starts its steady stream of oil onto the ex mans, only then do you find the right bank cassette failure. My JB is cured now, I'm throwing caution to the wind and installing my newly designed "decleration side cassette positioning bolt protection slide, thing". It was running and sounding fine with it missing (lodged down under) let's see what it does hanging from that positioning bolt (pivot point).

 

[shucker1]

Let us know how it works out please?

 

[masospaghetti]

I may be mistaken, but it seems to be an engineering flaw to EVER have a curved traction-side guide for a timing chain. I'm sure Ford did it for packaging reasons but still a terrible design.

Plastic guides in general make sense since they are designed to wear - not the chain. It's a sacrificial part. A better design could have been a soft metal (like brass, which is often used in bushings for similar reasons) or a roller design. But plastic guides are fairly normal for this application. The main problem is that a sacrificial part isn't easily replaced, and by making the traction side of the chain guide curved, it accelerates the wear of the part.

So why did Ford do it? Almost surely to save money, so they could use the same manufacturing methods to make the guides as other engines instead of producing special tooling or materials for these guides.

To review other factors why the SOHC engine is poorly designed, let's review the main advantages of overhead cams in general in engine design.
1. To reduce valvetrain mass (pushrods mostly) to allow higher RPM operation without valve float,
2. Provide additional control over cam timing (for variable valve timing), since a pushrod engine using a single cam and therefore valve timing for intake/exhaust can't be changed independently, and
3. Simplify packaging for 4-valve designs.

Now let's look at how the 4.0 SOHC fails to capitalize on these advantages.
1. The SOHC engine is not especially high revving - there are plenty of pushrod engines that redline higher. GM especially has made a ton of them including the 7,000 RPM redline "smallblock" 427, but even their pedestrian engines redlined over 6,000 RPM. See their 3500/3900 series motors.
2. The SOHC engine does not have variable valve timing.
3. The SOHC engine uses a 2-valve head.

Essentially, Ford could have made a higher flowing OHV head and gotten the same output without all of the engineering complications of going with overhead cams. The bottom ends of the OHV and SOHC are essentially the same so there is no advantage there, and part of the airflow advantage of the SOHC engine is the dual-runner intake manifold (although not all of them had this). I wonder if it was more of a marketing ploy because people associated overhead cams with high performance and cutting edge engine technology, rather than an actual design reason.

Ford apparently arranged the timing chains to use identical LH/RH heads and reduce manufacturing costs. Sounds plausible, although the LH/RH heads are actually not the same, so I wonder how much money they actually saved with this. Whatever money they saved is clearly not worth the added maintenance expense of pulling the engine to replace a wearable component.

Despite this, many SOHC engines last a long time, and they have a reasonable power/fuel efficiency mix that was fairly good for it's era. There are literally millions of vehicles with these engines still running around in the wild.

This is all conjecture so feel free to (constructively) criticize me.

EDIT: I realized I got a bit off topic here, apologies in advance

 

[imp]

@96eb96 Never expected to see "Victor Reinz" here! The Victor name was originally "Victorowycz", two Polish brothers who began making gaskets in their garage in the early part of the last century. The company they founded was Victor Mfg. & Gasket Co., in Chicago. Everybody used Victor gaskets, from OEMs to shade-trees. Turned out, I joined the Victor Co. on Sept. 21. 1963 as a Development Technician, charged with attaching and using strain gages on diesel cylinder head bolts. Ever see the bolt stretch dynamically every time the cylinder fired? We did!

The Victor family sold their company in 1966 to the giant Dana Corporation, the makers of Spicer U-joints and driving axles, for a paltry 16 million dollars. Thus I became a Dana Employee. I quit the company in 1972, only to return in '78 after getting my Engineering Degree from UNLV, to become Chief Facilities Engineer at the Dana Victor Churubusco, Indiana Oil Seal Plant. Somewhere during following years, Dana bought Reinz, the German Co., and attached it to it's Victor Divisions.

Small world! imp

 

[Foz1359]

Alright, got it all scotched up except for a couple things... can I reuse the old throttle body gasket (took tb off to clean) and here's a big concern... I want to spin the engine over for a few to build some oil pressure and also listen to what's what before I get fire in the holes. I have the plug wires off but I dont want to dump a bunch of fuel into the holes prior to my first startup. Is there a fuel pump relay or fuse (both?) that I can pull to build some oil pressure?

Small world! imp[/QUOTE]

 

[imp]

Alright, got it all scotched up except for a couple things... can I reuse the old throttle body gasket (took tb off to clean) and here's a big concern... I want to spin the engine over for a few to build some oil pressure and also listen to what's what before I get fire in the holes. I have the plug wires off but I dont want to dump a bunch of fuel into the holes prior to my first startup. Is there a fuel pump relay or fuse (both?) that I can pull to build some oil pressure?

Small world! imp

[/QUOTE]
@Foz1359
It's 2005? If same as '04, fuel pump relay in "Battery Junction Box" underhood. Check owners manual for diagram to locate. Standing by left fender looking in, the FP relay is the center one of the three closest to you, lower left looking into the fuse box. imp

 

[Foz1359]

Thank you IMP!

 

[imp]

Thank you IMP!

@Foz1359

De Nada

 

[Foz1359]

Well after a looooong delay, we were able to get the Ford back in gear today and she fired right up with no unusual racket, clanging or banging. We did pull the 20A fuel pump fuse and spin her over a few times to pump oil pressure and listen for any obvious problems. As she was running we noted a real bad miss and after some "ah craps" and "what this time" we pulled the non firing #1 plug and promptly discovered it wouldnt thread back into the head without hanging up after a few threads. Bummer. Trip to the parts house, chased threads, installed new plug and after a few white flags thrown and picked back up we bought a new set of plug wires. Man this truck runs great.

The photo shows (top looking down) the guide pin with the salvaged guide JB'd to the guide pin. I used some blue thread locker when I resinstalled the pin and positioned the thing-a-ma-jig as away from the chain as it would go. Hope it stays there for a few 10,000 miles. We'll see.

Thanks for all the support and I'll try to update you guys in a few months.
Mike

 

[Mbrooks420]

I think I would have just used factory timing components and a pre-oil and went on my way.

Trying to improve something is great, but if you end up lunching a motor over it, it kinda sucks.

I’m also not sure I’d trust JB weld in a constant hot oil environment.

 

[Foz1359]

I think I would have just used factory timing components and a pre-oil and went on my way.

Trying to improve something is great, but if you end up lunching a motor over it, it kinda sucks.

I’m also not sure I’d trust JB weld in a constant hot oil environment.

You're very right, OEM is def the way to go (appears to be of German manufacture -thanks be to those timing chain in the rear morons). But pulling the engine out in my driveway wasn't /isn't an option. Finding a place and the time to do it wasn't/isn't either. Buying chains, cassettes, guides, plungers, widgets, oil pump, oh, and the special tool kit required for holding the cams in timing, nah. This truck has 150k on it and no sentimental or street value. We paid $1700 for reasonably good cosmetics and regular oil changes (previous owner) and if we can get a few 10k miles out of it by surgically removing the broken half of the right bank timing guide and rigging it as a guide pin protector, I consider it all gravy If, not, well what the heck, I shoulda done my homework on the 4.0L before buying one.

My point at this point isn't to find the best methods or engineer improvements, it's to see what might get me going without spending more than the truck is worth. For today, we've done that -I'm driving it now.

Tomorrow is not assured for any of us anyway.

God Bless.

 

[donalds]

I would put the least amount of pressure on that j b weld joint and install a manual tensioner

 

[imp]

I think I would have just used factory timing components and a pre-oil and went on my way.

Trying to improve something is great, but if you end up lunching a motor over it, it kinda sucks.

I’m also not sure I’d trust JB weld in a constant hot oil environment.

@Mbrooks420
Given the additives in modern motor oils, as well as the chemistry of the oil itself, I suspect hot engine oil will slowly dissolve in that environment. imp

 

[masospaghetti]

GEARS are the only realistically-sound way to drive crankshaft-driven overhead camshafts, IMO. What about driving the camshafts directly with a stepping motor? Feasible? Has it ever been done? Could dynamically change timing while running.

Everything is a design compromise. Gears are certainly the most reliable but are going to cost significantly more, and cause packaging issues (bulkier) that reduces the amount of usable space inside the cabin for a given class of vehicle. Most well designed timing chains last well over 100k miles before they need to be serviced. I thought Honda engines' timing belt design was dumb at first but the belts are cheap and relatively easy to replace. The key is to make wearable components serviceable.

I did hear of experimental engines with electronically actuated valves. The ultimate design would be solenoid-actuated valves and no cams at all but so far nobody has figured out how to do it. Would be interesting to use a motor to drive the cam, certainly seems doable.

 

[Tech By Trade]

I wish I had access to a CNC machine and the know how. I would take apart one of those plastic guides, and clone it out of metal and mount a teflon or plastic running face to it for the chain. Would probably never have to look at it again.

 

[shucker1]

I wish I had access to a CNC machine and the know how. I would take apart one of those plastic guides, and clone it out of metal and mount a teflon or plastic running face to it for the chain. Would probably never have to look at it again.

I'll bet you could sell quite a few sets...