Cruz'nLegend

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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1990 L Coupe
white w/tan lthr
Michelin Pilot XGT's
185K and purrfect!