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Old 06-20-05, 03:13 AM   #1 (permalink)
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Noisy HLA's: Causes and Diagnostic Procedure

Part I

There has been a lot of discussion on this and other forums about the HLA (hydraulic lash adjuster) noise that’s so common among our older G1’s with no clear overview or overall diagnostic procedure presented. There have been many questions raised and many abstracted theories presented such as what it might mean if you only get the ticking on cold start and it goes away when warm; what it means if thinner oil or thicker oil is what helps; why the Auto-Rx and Seafoam treatments seem to vary the symptoms so much during the treatments and have such varied results; why Friction Free 3000 seems to work in some cases and not in others, etc., etc. Some of the rationale has been based on sound principles and reasoning, such as Greylegend’s ideas about the successful use of thinner oil meaning restricted oil feed to the HLA’s and thicker oil compensating for higher mechanical clearances (wear), or that a possible reason for Auto-RX treatments occasionally causing more noise in the middle of the treatment is due to the sludge cleaned off of some surfaces being deposited in other, more restrictive areas (i.e., the HLA oil feed hole and/or check valve), etc. But diagnostically, other than making us feel better about whatever it is we’re doing the theories are usually moot: they simply do not take into account all the possible variables that can contribute to the effects we’re experiencing.

For example, ticking when cold which goes away when warm can be caused or contributed to by too thick an oil being used for the ambient conditions; a restricted HLA oil feed hole; a sticky HLA check ball that frees up at a particular temperature; clearance between the HLA and the well it sits in that requires X amount of flow to overcome (not very likely but theoretically possible); clearance between the HLA plunger and HLA body so that it takes some time for the HLA to “pump up”; an oil pump that has just enough radial or axial clearance to take a while to warm to tolerances and get the oil moving, etc. In 27 years as a certified auto tech I found that quite often it’s a combination of such factors that create the symptoms in each case, and that many of them may counteract each other or, conversely, compound each other.

In overview, HLA noise can be caused or contributed to by anything that increases the lash between the HLA and the valve stem, from a lack of oil pressure to wear in the valve train. Oil pressure problems can be from a dented oil pan; clogged pickup; pickup-to-pump seal sucking air; worn oil pump; worn main and/or rod bearings; restricted oil filter w/ a defective or ill-designed bypass; restricted oil metering orifice between block and head; restricted head passages; varnished or sludged-up HLA oiling wells; restricted or clogged HLA oil feed hole; or sticking HLA check ball. Wear-caused HLA noise can be from the exceptional length of the exhaust valve train (more wearing surfaces – a peek at the online manual’s diagrams of the valve train tells the story), cam lobe and follower wear, or the HLA itself (plunger-to-body, check ball, or body-to-cyl.head bore which also lowers the effective oil pressure at the HLA). And imagine what happens when these interact with each other! Is there anybody here who seriously believes that low oil pressure stops with the oil pump? Or that cam and follower wear stops there, with no other parts of the engine being affected?

And another thing: doing an Auto-Rx treatment when you have excessive valve noise doesn’t make much sense. The treatment takes at least 5000 miles during which your engine can suffer a lot of additional valve train wear. Granted that if it’s only minor and brief it’s probably not going to be all that big a deal, and in that case if you’re too broke to afford a pro diagnosis and disinclined to DIY Auto-Rx is a viable approach if you know you have good oil pressure– at least you’re doing something! But it’s just as likely to fail as work, and if it fails you still haven’t eliminated deposits as a contributing factor as you can’t be absolutely certain that the HLA oil feed isn’t still restricted, the check ball sticking, etc. And unfortunately Greylegend is right: Seafoam, kerosene, Ford ATF and other treatments that are more chemically aggressive may dislodge larger particles that get stuck in the HLA or some other critical component and cause even worse problems. So that approach also has its risks.

A far better approach is to do an overall check of the engine. First to consider in that regard is that worn-out HLA’s is pretty far down the list of probable causes. Many so-called "worn" HLA's I've seen -- from many different cars, not just Acuras -- have merely had plugged oil holes leading into the HLA's high-pressure chamber or sticky check balls that "clean while you drive" concoctions haven't unplugged! If the HLA’s are truly worn out the likelihood is that you have wear issues throughout the engine – IOW, an engine worn enough that you might be better off doing a JDM or rebuilt. Likewise, with a cam and followers worn enough to replace there’s a very high likelihood that such a condition was caused by low oil pressure, poor feed to the heads, infrequent oil changes and/or poor quality oil and filters being used, or repetitive hard high-rpm use and/or overheating. So here also there’s a high likelihood of everything from the head up and possibly the whole engine exhibiting high wear. But then again, if you elect to do a JDM there’s no guarantee you won’t end up with the same HLA and other associated problems so you’d be well-advised to inspect the bearings, oil pump, cams, and valve train as well as changing the T/belt, tensioner and water pump before installing it. With all that in mind it seems a no-brainer that investing a bit of time checking out your old engine thoroughly to ascertain it’s overall condition before condemning it or dumping a ton of money in it is definitely worthwhile.

(*note: the detailed, full-version diagnostic procedure comes first followed by a discussion of short-cuts at the end, with a prioritization and explanation of likely causes. So you can skip to the “shortcuts” section and read the full procedure last if you like. But there is much in the way of explanation and procedure you’ll need to fully “get” the shortcut procedure so you should read it all before reaching your own conclusion as to how you want to proceed.)

Continued in Part II (next post)
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Old 06-20-05, 03:15 AM   #2 (permalink)
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Continued from Part I:

First, pull the oil press. sensor and check the oil pressure with fresh oil, a new filter (OE Toyo Roki, NSX, Mobile 1, Denso, STP, and the larger Wix are recommended), and the engine warm. Specs are a MINIMUM of 20 psi at idle, and a range of 72 to 82 psi @ 3,000 RPM.

1) If the oil pressure is within specs use a stethoscope or other listening device to try and isolate which bank the noise is coming from and whether it's the exhaust or intake valves. It's usually the exhaust valves, and usually on the rear head (more heat). Then let the engine cool off to ambient temperature, pull the side and top covers and adjust the exhaust valves per the manual. Note which ones needed the most adjustment and particularly those that correspond to the noise locations you identified with the stethoscope. (pictures and procedure on pg # 5-29 of the pdf)

The valve train on the exhaust side is quite a bit longer and more complex than the intake side and is exposed to a lot more heat so it will tend to wear more than the valve train on the intake side. This results in excess clearance in the valve train that the original setting may not be able to compensate for and is the main reason that Acura provided adjustment on the Exhaust side. And yes, the exh valve face and seat also wear faster tending to compensate for the valve train wear somewhat, but in my experience it's unusual for it to equal the valve train wear, especially on the rear bank. While it's true for most engines that the exhaust valve clearance tightens up more than the intake the length and reciprocating weight of the G1 exhaust valve train tends to ensure the opposite in most cases, especially when the engine has been operated at higher RPM's a lot (which, generally speaking, means manual trans cars more than autos). IMO, with 120,000+ miles on the engine the exh valve adjustment should be checked in any event, and sooner if the HLA’s are noisy.

Replace the covers using new gaskets and grommets, start the engine and check for noise. If there is none you’re done, but if there’s still noise note if they’re the same ones you first identified and proceed to the next step.

2) Remove the top and side covers and examine the camshaft and followers (also called the ”inside rocker arms” on the exhaust side and just plain old rocker arms on the intake side) and exhaust “outside” or lower rocker arms and shafts for wear. If you can grab an “outside” or lower exhaust rocker arm and twist it at all on its shaft both shaft and arm should be replaced. If the cam lobe faces have a noticeable ridge on the outside edges (face of the lobe immediately adjacent to the cam/follower contact area) the cam and followers should be replaced (see step 3 for procedure). Note also that if the cams are burned (dark brown to blue-black lobe faces) there is a good chance that the entire engine is worn out and should be replaced, so you’ll need to step back and do some reevaluating at this point to avoid throwing good money after bad. This “burned’ condition I’ve admittedly found to be quite rare on Legend engines and it’s something you’d almost certainly be getting other, more serious symptoms from, but it’s something to look out for. If in doubt get a pro to look at it.

If you find problems with any of the above and they ALL correspond to the locations of the ticking noises that you noted at the beginning of step 1, above, you’ve probably found your culprit(s). But whether you’re sure of that or not – and certainly if you didn’t find anything wrong in step 2 -- I’d still recommend step 3 for the sake of thoroughness.

3) If you haven’t already done so disassemble and remove the cams and rockers as necessary. Remove the timing belt upper covers and wire the t/belt to the cam gears securely (fine gauge mechanic’s wire works great and electrical wire is workable). Loosen the T/B tensioner and compress the belt to gain maximum slack in it as you re-tighten the tensioner bolt, then unbolt the gears from the cams and move the gears and belt out of the way as much as possible (if you do this right you won’t have to retime the belt but just re-tension it upon reassembly). Next, remove the cam bearing caps slowly and progressively, each cap a bit at a time, to remove the cams followed by the followers (“inside rockers”) and exhaust pushrods (*note: Be careful to keep all parts organized so that they go back into their original locations -- this is very important as once parts are worn together they may not work properly with parts of a conflicting wear pattern and will most certainly wear much faster because of those different wear patterns). Then remove the HLA’s from their bores and soak them in some suitable form of varnish remover (carb cleaner, kerosene, etc., NOT gasoline!) for at least 8 to 12 hours and preferably 24 hrs or more – again, making sure you don’t mix them up (separate, labeled containers for them along with their matching followers and pushrods is a good idea).
*caution: DO NOT use compressed air to “blow out” either the HLA oil feed hole or plunger as you may create a bullet flying around the room!

After the soak and while still in the solvent/cleaner bath bleed the HLA’s repeatedly according to the procedure outlined in the manual, then do it again in clean engine oil. This will hopefully clean any remaining varnish and particles out of the HLA. Then check the HLA’s per the online manual at pg # 5-25, or better yet, take them to a reputable Acura specialist or dealer to have them checked. Clean and check the HLA bores in the head and fill them and the oil fill holes in the head with oil per the manual. Replace any HLA’s that fail testing and reassemble the valve train parts in exactly the same positions they came from, ensuring that they have a good coat of oil on all the wear surfaces.

Readjust the exhaust valves per the manual, install the covers, and retest for valve train noise (*important note: be sure to use the pre-lube and special start procedures specified in the online manual)

4) If you still have noise and you’re sure that the oil pressure is OK then first check that you have oil to the HLA’s (you did the pre-lube correctly and cranked the engine ‘till you had pressure before starting, right?). If you’re sure that’s OK then recheck the valve adjustment. If you still have noise after that you may need to replace some or all of the HLA’s that were cleaned but not replaced or you missed something else wrong in the valve train. But don’t just assume they’re bad, really make sure they’re getting oil pressure and the adjustment is right before condemning them.

1) The very first thing you need to do before tearing into the bottom end of the engine is make sure the top end hasn’t been worn out from the lack of oil pressure. You don’t need to disassemble the valve train at this point, just pull the covers and look for obvious cam, follower, and rocker wear, incl “burned“ blue-black cam lobes. If you do find excessive wear or cam burning you’ll want to seriously weigh the costs of repair against a JDM before you start replacing parts.

2) If the top-end looks OK inspect the oil pan for serious dents that might impede the oil pickup. Even if the pan isn’t bad you’ll have to pull it to inspect the pickup and screen as well as to remove the oil pump and inspect it. So as you’ll need to pull the pan anyway you might as well pop some rod and main caps and plastigauge the bearings. Check the clearances on the main bearing closest to the pump as this has the greatest effect on pressure, and clearances on the furthest rod bearing as this will usually show the greatest wear. This is of course IF you’ve done it before or have someone who has that experience helping/guiding you. Plastigauge kits and directions are available at most auto parts stores, but the handling of the bearing surfaces and their replacement requires meticulous cleanliness and assembly or you can destroy your crankshaft and possibly your engine. Otoh, as bearing wear is a major cause of low oil pressure next only to a worn oil pump it’s important enough to warrant having an experienced tech look at a couple of caps if you can’t tell, yourself. With some experience one can tell by looking at the bearing surfaces whether they’re totally shot or not, saving you the effort of plastigauging if they’re obviously worn out (clue: if they’re not an even dull-lead gray but have shiny spots they’re probably shot. You can also compare against new ones at an auto parts store). But even an experienced tech will NOT necessarily know whether they’re worn enough to cause low oil pressure, especially if the wear is even and hasn't penetated the babbit material. For that one must plastigauge.

3) If the pan, screen, pickup, and bearings are all OK you need to R&R and check the oil pump. Personally I’d replace the pump automatically if there’s low oil pressure and the pan/pickup are OK (incl the pickup-to-pump seal) because if the bearings are worn the pump almost always is, too. And if the other items are OK it pretty much leaves the pump as the cause unless you have something completely off-the-wall like a weak or stuck oil pressure relief valve (and which in all my time as a tech I've not seen even once!).

The oil pump is on the front of the motor behind the timing belt and oil filter housing so you’ll need to remove the belts, frt. motor mount, crank pulley, frt covers, and drop the t/belt per that section in the online manual. Then remove the oil filter housing and, with the pan already off, the oil pan baffle, pickup, and oil pass pipe. Now you can remove the pump bolts and pump to inspect it per the manual You’ll need a perfect straight edge and a set of feeler gauges, or take it to a dealer or Acura specialist. Better yet, just replace it!

If you don’t want to automatically replace the pump and it checks out within specs, plastigauge the rod and main bearings if you haven’t already done so. If the rods and mains checked OK, replace the oil pump anyway “for cause”. Reassemble per the manual and recheck the oil pressure. If it’s now within specs and you still have noise follow the procedure under “Oil Pressure Normal”. If the pressure is still low you missed something or reinstalled something incorrectly – probably the pickup or pass pipe or possibly you didn’t get the pump correctly sealed, assuming you properly plastigauged the bearings. So follow the manual VERY carefully during the reassembly.


It’s obvious that not everyone is going to be capable of doing the entire above procedure themselves and many of those may not be willing to pay a shop to do the whole thing, either. But it’s still a good idea to do at least the basics: an oil pressure check and valve adjustment followed by an Auto-Rx or Seafoam treatment if you have good oil pressure and have at least a fair indication that the rest of the engine is in pretty good shape. So,

1) Check the oil pressure. If you don’t have access to a good gauge and/or don’t feel competent to DIY it’s a pretty cheap test in most pro shops. But if you can get a gauge (rent one!) it’s really just taking the wire off the oil pressure switch above the filter, unscrewing the switch, screwing in the pressure gauge fitting, turning on the engine, and reading the gauge (with the engine warm, of course).

2) Pull the top and side valve covers, inspect the valve train for unusual wear or scorching, and if there's nothing major adjust the valves. Again, it’s not all that much money to have a pro shop do this if you feel you’re not up to it yourself. However, the valve adjustment is pretty easy if you follow the procedure outlined in the manual, and even if you can’t tell, yourself, whether there’s unusual wear or discoloration of the cam and followers you can take pics and/or describe what you’re seeing and post it on this forum. Somebody here is bound to have the knowledge to help you out even if I’m not around.

3) At this point you can decide how to proceed based on the probabilities and your budget. If the oil pressure’s low but there appears to be no top-end damage you can decide whether you want to replace the oil pump, have someone do it for you, or just “punt”. If the oil pressure is low and there is top-end damage, you’ll need to do some careful checking of what it’s gonna cost versus what a JDM is gonna cost. Or again you could decide to punt. If the pressure’s OK but there’s visible top-end damage you can decide whether to just keep driving it or punt, and if there’s no top-end damage whether you want to go after the HLA cleaning and testing or hope that a long Auto-Rx treatment (or something stronger) will take care of it. One way or another, you make your choice and pay your money!

4) Or, you can opt for the guaranteed cure: go get sh**-faced. You won’t hear it anymore and won’t worry about it either. . . :rofl2:

PS; Whatever you decide as to which procedure you follow or repairs you do or don't make I recommend using a good synthetic oil in either 5w30 or 0w30 weight -- after you use a good seal conditioner or an Auto-Rx treatment (it has very good conditioners in it). The flow rate of synth is much better than dino oils even though it may have the same viscosity rating, and synth oils generally have better additive packages than dino oil. But while synth will flow through the very tiny HLA oil supply hole better it will also leak through seals easier unless they're in good condition. And that applies even if you've replaced all the engine seals -- over many miles the surfaces on the crank and cams that the seals rub against also wear reducing the seal tension against them.

The best synth oils (by empirical testing rather than just my opinion) are Mobile 1, Royal Purple, Amsoil, and Castrol Syntec (German-made ONLY, as US-made isn't a full synthetic). Sorry, I haven't seen any tests yet on Quaker State's new "Q", but their old stuff didn't test as well as the others (which is probably why they had to come up with a new line!). The better filters I've already listed above.

Also, it's been brought to my attention by Greylegend that I omitted another important preventative factor: one should clean and check the PCV valve on a regular basis, and replace it at least every 60,000 miles. A malfunctioning PCV can cause oil dilution (fuel and other caustic byproducts) that leads to inadequate lubrication and thus increased heat & oxidation (sludge and varnish!).
1990 L Coupe
white w/tan lthr
Michelin Pilot XGT's
185K and purrfect!

Last edited by Cruz'nLegend; 06-23-05 at 03:53 PM.
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Old 06-20-05, 09:16 AM   #3 (permalink)
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DAAAYYYUUUMMM! Do the fingers hurt from all that typing Larry? lol..just kidding! I have a little bit of lifter tick and I know I have good oil pressure, so I'll probably do the Ford ATF treatment. I've got a decent amount of sludge in my Legend's motor. Thanks for the great info.
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Old 06-20-05, 01:26 PM   #4 (permalink)
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Sticky this ASAP Lee

You're the man Larry
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