Recently my 1994 Honda Passport 3.2 started to having this lound tapping(knocking) sound under the hood. It only disappears when I maintain certain speed or accelerate, maybe it related to RPM.
Searched on the Internet and found lots of people have the very same problem from their ISUZE Rodeo. Seems most people fixed their problem by replacing timing belts and the hydraulic tentioner. I was wondering:
1) How much roughly will that cost: parts + labor
2) Should I take it to the honda dealership or Isuzu's? Or maybe I'd better take to a little garage to do it to save a few $$$.
I had the timing belt, tensioner, idler, all belts and water pump replaced at 118k miles on my '94 Rodeo 3.2, 4X4. It cost me $1000.00 at the local (very reputable) garage here in Massachusetts. I had the same knocking noise at certain RPM. Turned out it was the hydraulic tensioner for the timing belt. I had them do the water pump and idler since they were going to be in there anyway. This was a repair I did not put off in any way. The truck was in the shop the first day I heard the knock. I believe that if you loose the timing belt, or if it jumps you loose the valve train.
I called the local honda dealer up last night and they quoted me over
900$, even though I told them I only need a hydraulic tentioner. Damn expensive. I was wondering will ISUZU dealer do this? Any one tried on little garage? My 4X4 has about 140K miles on it now. I could drive around with this problem but it bugs me the heck out of it.
Read your post. If your "tapping" sound comes and goes with RPM, then it could be just what you have found. If it comes and stays, it could be a little more intense. I have a '95 Passport which has (hopefully soon "had") a constant clicking/tapping sound on one side of the head which turned out to be stuck hydraulic lash adjusters (aka lifters). This is an expensive repair from the dealer standpoint (upwards of $1,900 parts/$3,000 labor), which is why I have decided to do it myself. I am just at the point of reassembly and have saved A LOT. I am replacing my timing belt at the same time as well as all my belts.
The work, while difficult, has been pretty much straightforward. Fun, even, dare I say? Although, not being the journeyman mechanic, it's taken quite a long time and it's good to have a friend who's a mechanic by trade to be able to answer a few questions. A digital camera is immensly helpful.
There is a service bulletin from Honda (Izusu I am sure, as well) which details the HLA problem/fix.
Thanks for your helpful reply. I found the sound comes as soon as I starts the engine and goes when RPM >1750. It is kinda loud because I could hear that when I am driving with window shut. I hope the problem won't be that server because I am not that mechanical savvy like you...LOL... ANyway, I called a ISUZU delaer the other day, they said they would do it for $560, much better than HONDA.
I've seen a Honda recommendation of a 0W30 (not 10W30) oil for this problem as well, assuming the clicking is something beyond just the hydraulic tensioner, as the previous poster seems to be implying, as I did in a previous posting as well. Apparently, the 0W30 oil allows air into the HLA (Hydraulic Lash Adjuster) in an assist to free up the carbon buildup inside which is the cause of the HLA (aka lifter) sticking in the first place, thereby causing the clicking sound. 0W30 oil is a bit rare and harder to find (at least in my experience) but Mobil makes this brand and should be readily available in a local auto parts store.
Well, it wasn't that bad, but was loud enough for me to hear it inside the passenger compartment with the windows rolled up. So I guess it must be loud enough for others to hear it, too. Mt father used to have a Cadillac that had a distinctive sound like this. It was just one of those things. The sound I have in my Passport isn't distinctive but a sign of something wrong.
I am now about 85 percent complete with the rebuild process. I do hope that when I start the engine the sound is gone. I'm sure it will be. Found some pretty bad rocker shafts in there. And ended up replacing all four of them, two on each side. All of the lash adjusters have been "rebuilt" and four on one side were suspect of the clicking sound and one on the other (where there was no clicking sound at all present) was just STUCK. It's now been unstuck. :) I am so sure that had I not addressed the side of the head which was not having a problem -- and after having discovered how bad off it really was -- that I would have experienced the clicking sound just at about the time I was happy to have the sounds coming from the other side gone.
The clicking sound, I've been told by many, is a sign of untimely oil changes. Without proper lubrication, the rockers and shafts end up scoring each other and the lash adjusters fill with carbon and don't allow the proper clearance between the rockers and the valves. Thus a clicking sound develops. There really isn't anything you can do except live with it, perform the proper procedure to fix the problem, or it will just get worse/louder until eventually things score away so badly that engine performance is majorly affected.
Wish I would have taken before AND after pictures. Only have some before ones. Major difference seen.
As a P.S. to the original poster (I don't have the original post), I ended up having to reload my Hydraulic Tensioner with fresh fluid (about 1/2 ounce) due to the fact it was laid out upside down one night and some fluid leaked out causing it to not load properly. I just took it apart and cleaned all the parts, coated them with fresh fluid and put them all back together. Went back in fine.
Would save you a lot of money to do it yourself this way. Otherwise, I found one online for around $60.00, not the price you were quoted.
Some info I found on other web board and seems to be helpful. I will try to listen to mine passport's engine. I kinda lean towards time belt tensioner as mine has not been changed for a while...
" try using a scredriver as a listening tool place the tip on the rocker arm cover and your ear to the handle while the vehicle is running while listening try moving the screwdriver to find the point where the noise is looudest try both left and right banks please donot try this at the front of the engine for you may injure yourself let me know what you find you will most likely find your concern is noisy lifters what is you oil pressur elook like shoould be at least 45 psi at idle if not remove you oil pan clean your oipump pickup tube and be sure the screen is not pushed up against the tube for this will cause loss of oil pressure. With this kind of milage your rocker arm cover gaskets are probably leaking replace them and whle you are there replace the plug tower seals ,then on the left head at the front there is a releife valve remove it and clean it,same thing on the right but the valve will be on the rear of teh right head. If theser are stopped up it will cause tapping in the top end of the engine (let me know) if you need more info Oh someone may tell you an engine purge may work I am an Isuzu Tech and have tried it a number of times and have never seen it work. If your concern is in the front of the engine it is most likely your timing belt tensioner especially if it has never been changed (never reuse the tensioner if you remove it replace it) if you do go there check the water pump for the timing belt must be removed to replace it and they usually last only about 150,000 miles before they start to leak from the weep hole on the botom side of the pump "
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