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4-cyl. V-tek engine knock 1994 HONDA

Recently gave up my Delta 88 Olds “truck,” used for many yrs. as a work vehicle. My wife refused to ride in it. Bought a '94 Honda Accord, look-good wagon, which, I find, holds less than the Olds and at 142K, has 20K more miles than Olds. The engine’s a 4-cyl SOHC VTEC. Because I bought it through a friend selling it for his daughter, I didn’t check it out as well as I should have. Big mistake. I’ve found myriad problems over the last month of ownership, most, just annoyances. However, my main problem/concern is the light knocking at various, but not all, r.p.m. Especially noticeable around 2000, the knock is magnified in exhaust pipe and cat. conv. and it bugs me to no end. I’m concerned that the engine may have overheated at one time. I noted dark brown, solid stains on the dip stick .
What I’ve done: Checked plugs (all loose and not NGK, readjusted gap, and reinstalled. (Plugs/wires were changed about 20K ago.) Checked a few other things and decided to check the plugs, again, just in case. I found all four loose, again. Thinking it my fault, I repeated the process, came back 10 minutes later, and found one loose, again! Knocking still obvious, too. Next step: Took to Honda garage, and had them check timing. Mechanic found it off by 20-degrees and adjusted. I asked about knock. He listened and did a little gynaecological exam and told me it sounded/felt like a loose timing belt. I mentioned that the prev. owners replaced @50K & 8-years ago. He said it’s overdue because of its age. I also explained the plugs problem. He attributed that to the wrong brand. I later changed them, but the knock, although quieter, persisits, AND the plugs still loosen after just a day of in-town driving–not as much as old ones, but still not tight. I’m thinking, again, overheated engine and affected head.
Told all this to a friend whose mother used to drive a 1994 Honda. He said that engine always had the same knock as mine does. My mom still drives a 1995 Hon. (30,000K!) and I’ve noted it’s a bit noisy. Since she lives in another state, I can’t easily check it out. Any thoughts? Thanks.

IIRC only the EX sedans got the VTEC engine in 1994. But anyway this car is overdue for new timing belt. It’s possible that head is damaged if the spark plugs keep coming loose.

First let’s address the sparkplugs. These plugs may not be the correct ones and may have been forced in…or put in sloppily resulting in crossthreading. Buy a set of the correct plugs, compare the thread length and thread spec. The NGK website defines the part number codes (see the guide attached) for the correct plugs and the existing plug’s brand name site should give you their specs. You can also check the thread condition with a borescope if you’d like, or have a shop check. Overheating won;t affect the ability of the head to hold plugs.

Worst case, the plug holes would need to be tapped oversize and helicoiled.

Ignition timing was off 20 degrees? Advanced or retarded? How was the cam timing?

I have a sneaking suspicion that either the car has been messed with to try to make it faster, or someone was working on it that didn’t know what they were doing, perhaps your friend’s daughter’s boyfriend. It’s also possible that it’s suffering a damaged bearing due to having been run dry of oil. Kids often don’t realize they have to check the oil occasionally. Or a valve or a piston may be dinged.

Honestly, I’d do a pressure leakdown test (just in case there’s a breeched headgasket (it’d also tell you if you have a valve not totally closing due to damage), check out those spark plug threads and if questionable helicoil them, and probably take a look-see into the cylinders with a borescope.

Considering the age and mileage of the car, I wouldn;t tear it down. I might replace a headgasket if necessary, but that’s it. If it were getting my wife from point A to point B reliably I’d just accept it as an old vehicle, make sure it’s safe, get her a AAA card, and check the fluids regularly.

I agree with mountainbie about the conditions of the spark plug threads. If they’re damaged the plugs will not stay tight and may eventually blow clean out. The only cure is Heli-Coils, thread inserts, etc.
Someone probably got a bit ham-fisted while changing them.

If the timing was advanced by 20 degrees that could definitely cause a rattle and would be a bigger concern than the spark plug threads. The unknown here would be how long the engine was running around like that. If the engine is still rattling or knocking after the timing has been properly set it’s possible the rattle could be due to damaged pistons as excessive timing advance can eat aluminum pretty quickly.
If the car was pretty much used around town with that kind of advance then the in-town driving is the only thing that saved it at this point as a highway trip could have led to a catastrophic bang at some point.

An EGR fault or loose valve lash can also cause a rattle but with the latter this should be noticeable while the engine is idling.

The timing can’t be off 20 degrees, it is not adjustable. Loose spark plugs could make a knock so that needs to be addressed, but the timing belt should be priority 1. Also check those rockers.

The timing can’t be off 20 degrees, it is not adjustable. Loose spark plugs could make a knock so that needs to be addressed, but the timing belt should be priority 1. Also check those rockers.

'94 Honda Accords had a distributor based ignition system. Whether the distributor will actually twist that much I don’t honestly know, but the timing is adjustable.

I could see 20 degrees of movement in that distributor. It’s not just the length of those slots but there’s also a considerable timing swing based on the test connector being plugged in or not.

http://www.autozone.com/autozone/parts/Cardone-New-Distributor/1994-Honda-Accord-DX//N-j0zkhZ9n80u?itemIdentifier=690406_135675_4618

A VW fuel injected Bus went through a major service one time at the dealer I worked for, ran fine around town for a week, and then blew up once taken out on the highway. Several pistons gave up due to too much timing advance. In this case it was 30 degrees. Ouch.
This was going to reflect poorly on the mechanic who did the service and knowing he was very proficient, it was hard to imagine him screwing up this badly.

Come to find out it wasn’t his fault. It was VW’s new electronic equipment with the magnetic timing plug that was giving a severely flawed reading.
You should have seen the VW rep’s face go red on this one because corporate VW was dead sure the equipment was correct and the mechanic was at fault. :wink:

“I noted dark brown, solid stains on the dip stick .”

It’s piston slap due to infrequent oil changes.
I’ll bet $1 if you took off the head the cylinders will have a ridge you can catch your fingernail on.

Keep it full of oil, keep driving, and turn the radio up.

It has a distributor, but the timing is not distributor based, it comes from the computer and is based on the crank position sensor.

Thanks, guys, for all the input. I wasn’t clear about plugs. I did replace & properly gap new NGK’s after timing adjust. The engine, according to the lettering on valve cover and my manual, IS an SOHC VETEC. Many of the scenarios you all offered are those I suspected and feared. I think you’re right about letting the engine oil get low. Since the plugs are so deeply recessed, tapping and setting helicoils would be a real challenge. HOW ABOUT THIS IDEA? Loctite the uppermost threads and if removing plugs later, hold a vacuum cleaner hose over the opening to catch any pieces, after each turn of the wrench? We do have another, newer vehicle for my wife. Since I only use the H. in town, I just may opt for your idea of keeping oil full and radio up. Probably have to replace timing belt, though. Maybe the mech. was right & that’s the knocking source?? Thanks again. Roger

It’ll never work. The loctite will never survive the environment.

Having said that, try it. You have nothing to lose. And if it works, post back and I’ll have learned something!

If the knocking is due to the belt, then it has to be valves hitting pistons, but I don’t think that is the problem. at that point, the belt would not last for more than a few miles and you have already one beyond that. But it needs to be changed ASAP or the knock will be due to valves hitting pistons and it will be too late then. Seven years is the max on this belt.

If you are going to loctite the plugs in, then I recommend that you get the Iridium tipped plugs, they are good for 120k miles, just in case you can’t get them back out.

The V-TEC mechanism could be the source of your knock. If one of the pins did not retract completely, then the pin could be hitting the secondary rocker arm making the noise.

Thanks guys. A lot to consider, esp. the near $600 belt replacement job.

Roger

A 15 year old car with 145K miles,Circuitsmith gave you the best advise…

More confusion,here. The car looks lke new in/out and no history of collisions. Paid $2,600 (below book).
I do only use the car for my local handyman work, usually driving less than 15 mpday. So if I ignore the belt and it goes, do I kiss the $2,600 good bye? Roger

You will either kiss the $2600 goodby or $3500 if you replace the engine with a reman.

Well my wife has a 2000 Accord with the V-Tec ULEV engine,believe it had around 30K on it when she bought it(dont quote me on that) shes miles em out pretty fast,(she does home healthcare) any way aside from the timing belts really have done nothing but oil changes.Its had a funny racket forever in it kind of a rattley slap knock-but it now has over 174K on it,(did change the plugs the other day made it alot more responsive-got watch your speed now) and the racket now after all these miles has actually diminished,the only thing I ever found out about the car was the previuos owners Husband ran 10W-30 oil in it rather then 5W-30,I have always heard you shouldn’t second guess Honda on oil viscosity(I always use 5W-30)apparently the old timers think that low viscosity oil doesn’t lube as well-Kevin

Thanks guys for the continued input. Guess I’ll not risk the $2,600, get the belt changed, and pray that the noise disappears with the new belt replacement. Am cotacting Loctite (henkelna.com) tomorrow, to see what they think about using their product on the plugs. Roger