Did Timing Belt Change without Tilting Engine.....

[AcuraNSX]

I just thought I would give future prime members or those sitting on the fence about doing the timing belt themselves an opportunity to gain from my perspective.

First and foremost, it was EXTREMELY helpful to have Gary Kentosh's write up and contributions from Larry Bastanza. Larry encouraged me to read and really familiarize myself with the shop manual. Here is what I did with my 91 NSX with 121,000 miles on it that I had no idea if a timing belt had been done on it. As I am sure, most of you on this forum, would never want to take the risk either, but I at least knew it was changed at least once before since the lower timing belt cover had a cut out in it for the new style water pump weep hole. That being said, whoever did the work, did really great work, being that all the bolts were torqued perfectly, and the only problem I had was that he had forgotten to put the 10mm washer behind the bearing cover on the A/C idler pulley! As for the setup of the vehicle....look at Gary's pics, they will help you tremendously. It worked beautifully with the Honda crankshaft tool and handle. btw, I used a heavy 3/4" breaker bar to break the bolt loose.

So this was a pretty big undertaking on my behalf, spanning almost 3 weekends!

I changed the following:

Main Relay-car stalled once sitting idle in my driveway in September....once, is all it takes for me to do something that eventually will need to get done

Ignition Switch- preventative maintenance

23 out of the 24 coolant hoses (I have an Automatic transmission), I didn't bother doing the expansion tank overflow hose. As for their condition? 27 years and they were FANTASTIC! The japanese sure know how to make rubber! Trust me, they are a extremely difficult to get off after sitting on the car for 27 years. As Larry suggested, use a silicone base lubricant to slide the new hoses on. I used a 3M silicone paste I bought on amazon for $20, that is safe on all rubber, plastic, and electrical connections. I used it very sparingly, just enough to allow the hoses to slide easily over their respective pipes.

New OEM Honda Radiator- nothing was wrong with mine, but after 27 years, why take the risk, so I decided to change it. Also changed out the both lower radiator mounting cushions, why not...

OEM Thermostat, car fax showed it being done at a private garage, so I figured it wasn't an OEM product, so why not do it while I have all the coolant drained anyway.

Both Front and Rear Spool Valve gaskets- All 4 gaskets were replaced.....I noticed oily grease around the top and back sides of both so I decided to change them. I had noticed a leak on the garage floor for the last year, so I thought why not change them, since they would need to be done anyway someday. My advice, do what Larry says, and unbolt the black emissions box and flip it over to give you access to the front spool valve bolts. Don't bother disconnecting all the vacuum hoses, you don't need to. As for the resistance, 16 ohms on both front and rear spool valve and mechanically tested the plunger. All good.

Timing Belt- not only did I pin the cams with 4 punches as Gary recommended, but I did the white out marking technique...double counting, triple counting the markings on the old belt and the new belt. Btw, the old belt was in fantastic condition! Contrary to what the shop manual said, I was able to install the belt over the rear exhaust cam without advancing it a half tooth. I pulled the belt nice and taut over the crankshaft pulley, front exhaust cam, front intake cam, water pump and rear intake cam. It took a little coaxing but the belt went on fine with all the slack I had from moving the tensioner pulley all the way to the left and lightly tightening the bolt.

Water pump- replaced because it made a weird grinding sound when spun counterclockwise....clockwise was ok, but I didn't want to take any risk by keeping the old one in there. I also took Gary's advice and changed out the 9 bolts with new ones....I didn't want to take any chances here or left wondering

Tensioner Pulley and spring- nothing was wrong with mine, but I figured after 121,000 miles, why not give them a rest and put in new ones

I didn't need to replace the gasket on the lower timing belt, because mine was in excellent condition! All I can say is if you remove the oil pedestal entirely (remember, I was doing a coolant hose replacement anyway), you can easily remove and install the lower and rear timing covers up through the bottom....if any newbie is unsure, pm me and I can text you the video showing how quickly and easily they go in and out through the bottom without tiliting the engine one bit!

New Valve (Head) Cover Gaskets- prepped this by washing and degreasing the Valve covers completely and putting a thin coat of Honda Bond HT in the channel all the way around to hold the gaskets firmly for the intricate manipulation to get them positioned properly

New Spark plug gaskets in the Valve covers-use Honda Bond on these six plug gaskets to hold them in place prior to install.

OEM Harmonic Balancer aka Crankshaft pulley-my pulley was fine, but who knows when it could delaminate, as an extra precaution, I bought titaniumdave's CRF heavy duty timing belt shield and installed it behind the new OEM pulley.

New NGK Spark plugs.....mine looked excellent...all were similar in appearance and minimal wear...again, I had no records, so I decided to do them.

Cleaned up the Air Intake Temp sensor thanks to fantastic prime member's write up. Just do a search for "smog test failure", it's simple...mine was bad, just not as bad as the one in the original poster's thread.

VVIS screw inspection completed with a boroscope through the throttle body since I had the hose and air box off anyway. All 12 screws were on the butterfly plates....nothing dangling by one screw or anything.....

Coolant- follow the shop manual's directions to the letter and you won't have any problems. Do as Gary says in the timing belt write up....put the rear of the car up higher than the front. Yes, you will need 4 gallons of it...in my case a little over as I let a little bit too much flow out of the bleeders.

New Coolant Expansion tank and cap- Yes, I got the OEM Milk Jug...lol....read Kaz's write up and you will be simply amazed as to how much he and Honda engineers know....why reinvent the wheel...the old one was good for 27 years, but I didn't want to risk a leak after all this work....out came the old one and in went in a new one....recommend doing the front spool valve gaskets while the tank is out....

New A/C belt and Tensioner pulley....thanks Kaz for the clarification! Nothing wrong with my old one, but you get the idea now....who needs it seize up on you on the highway, so I replaced it with a new one...$82. By the way, the two long top bolts on the Idler Pulley mount, can be wiggled carefully without tilting the engine. Unfortunately, the idler pulley nut was the only nut I couldn't get my torque wrench on....I guesstimated the 36 lb ft...lol

New Alternator Belt

New fuel filter- All I can say is Larry Bastanza is right again! Thank you Larry! Put an air powered impact gun on it for safety! You could use electric if you had to, but better to just use an air powered one around gas lines. Broke the front 17mm banjo bolt easily! rear banjo bolt is easier to work on if you unplug fuel pump resistor, remove the bottom mounting bolt and loosen top one until you can swing the fuel pump resistor towards the left, this frees up space to break that bolt loose in 2 seconds. I tried to loosen these bolts without my impact gun and I thought I was like who the hell over torqued these bolts! Larry pointed out in a previous post, it's the crush washers that really hold that filter tight. Trust me, after an hour of monkeying by hand with these bolts, you're better off just using an impact gun! Btw, I flipped over my old fuel filter and out poured dirty brown fuel! I suppose it's been quite some time since it was last changed. Glad that I got it done! pm me if you feel like jumping off a ledge while doing this manually, I will talk you down! lol and then let you borrow my air compressor and gun if you don't have one.....


Brake Fluid Bleed-read the wiki pages on this

New OEM Air Filter

New OEM Oil Filter and Pennzoil Ultimate Synthetic 10W-30

New magnetic drain plug from SOS-let's see if we pick up any shavings....

As a final service, I compression checked the engine to make sure nothing got screwed up on the timing belt service and to check the overall health of the combustion chamber....results are posted in another thread.

Thanks everyone! And anyone who is embarking on this....feel free to reach out to me if you have any questions.....if I can't answer them, other primer members might be able to, and if they can't, I am sure Larry, and Kaz sure could! lol....

 

[Hass]

Great job. I also went with the milk jug on my recent replacement due to a small crack.

 

[AcuraNSX]

Thanks Hass! A worthwhile maintenance project.....

 

[nsxspdfreak]

Nice job!

 

[B2FiNiTY]

bravo, I wish I had the patience.

 

[goldNSX]

Your title says "without tilting engine". Any comments on this one?

 

[AcuraNSX]

Your title says "without tilting engine". Any comments on this one?

Please see quote from original post.....

"I didn't need to replace the gasket on the lower timing belt, because mine was in excellent condition! All I can say is if you remove the oil pedestal entirely (remember, I was doing a coolant hose replacement anyway), you can easily remove and install the lower and rear timing covers up through the bottom....if any newbie is unsure, pm me and I can text you the video showing how quickly and easily they go in and out through the bottom without tiliting the engine one bit!"


If you remove the oil pedestal entirely, the lower and rear timing belt covers come out easily from the bottom of the car. As for the A/C idler pulley, the two long bolts can be removed and installed without tilting the engine. Just angle them as much as possible and they will slide out of the timing belt cover quite easily. It might take a little fiddling, but it is very doable. as for all the timing belt cover bolts. They are ALL accessible from either the top or bottom of the car without ever tilting the engine. I never removed one bolt or loosened a single bolt on any of the engine/mounts. This way you don't have to worry about binding the transmission up/stressing refrigerant/fuel/brake/electrical wire harness lines whatsoever. Please remove the oil pedestal, (YOU WILL THANK YOURSELF) and replace those two coolant hoses on the pedestaleach time you do the belt change, they are very cheap in price, and will take you no more than 20 minutes to get off. Besides you either or doing the water pump, and/or coolant flush anyway. Apply 3M Silicone paste or Larry's recommended Pool O ring lubricant and they will slip on without much effort. If you don't have either, just dip your finger in some fresh coolant and coat the inside of the rubber hoses and outside of metal pipes to make the hoses slide on more easily. Trust me, it works on the smaller hoses really nicely! The thing with the oil pedestal removal is that it opens up the bottom completely for the rear and lower timing belt covers to be removed and installed easily. Hope that helps....if not PM me and I shall give you my phone number and we can go over it at length.

 

[goldNSX]

Thanks for the additional explanation. I was just wondering why exactly people tilt the engine. Better sight on the cams for timing the belt?

 

[AcuraNSX]

Quite possibly for viewing the rear camshafts timing marks more easily, but I could see the front ones perfectly aligned without tilting the engine. Besides, Kaz has pointed out that the bottom crankshaft gear has a mark on it that lines up perfectly with an arrow stamped onto the oil pump housing, when you are at TDC. You can see that without tilting the engine quite easily. I used the whiteout markings to make sure I didn't screw up the timing by 1 tooth or even more! Marking the old belt and new belt with whiteout is my preferred technique as an extra insurance policy. Besides the 4 pins used to lock the camshafts is yet one more way to make sure everything is aligned. Hope this gives you or anyone else attempting this DIY project the confidence to tackle it.

Thanks for the additional explanation. I was just wondering why exactly people tilt the engine. Better sight on the cams for timing the belt?

 

[Kaz-kzukNA1]

Everyone has their own way of carrying out the certain procedure and the level of skill/experience are also different.
Therefore, following advices are for those thinking of carrying out the DIY TB service on NSX eng for the first time with limited previous experiences even with other eng and no intension of denying the @AcuraNSX 's method.


Probably you are going to struggle using the holder tool at the rear exh cam while adjusting the TB tension without tilting the engine.

Tilting the eng will provide you with extra room when creating oil free surface at the rear bank #1 cam holder where the rear valve cover sits.
Still, not easy task while keeping the eng inside the bay.....

You don't want tilting the eng while installing the rear valve cover but removing the Eng and Gbox 'side' (R and L) mount bolts will help you during the process.
This will lower the Eng/Gbox assy just several mm yet this tiny amount makes huge difference when it comes to the rear valve cover installation.
Even with this extra tiny space, you are still very likely to be using the 90deg rotated method before aligning the valve cover to the cyl head.
Practice it before fitting the gasket to the cover.
You don't want letting the valve cover gasket touching any of the oily surface or disturbing the area with the liquid gasket applied.

If removing the oil cooler bracket (pedestal), you must clean the mating threads and replace two upper bolts or apply liquid gasket to the upper bolt thread before installation.

Before using the 'marking' method, please triple check that the existing TB is set at the correct timing.
By now, majority of the NSX engine went through its first TB service (although some of the late models in Japan haven't done it yet) and there is no guarantee that the last TB service was done with the TB installed at the correct timing.
Over the years, I saw several mistakes made even at the Honda/Acura dealers.

Please remember that the total number of teeth between the TB and the cam/crank pulleys are different that you only have one chance for relying on the marking.
Once you rotated the crank even for 1 turn, that's it.
The marking won't line up again until you rotate the engine for days….

You can't rely on the 4 x pin punch method on the early 91 engines.
The holes at the holder plate and the cam at the front exh side won't line up when the marking on the cam pulley was aligned against the marking on the cover plate or the top edge of the plate.
This is with the TB removed.
You may be able to insert really thin punch (like 2mm diameter) angled but not with the 5mm one.
If you managed to insert all 4 punches especially the one at the front exh cam on the early 91 engines, you better double check the timing using the markings on the cam pulleys and the crank drive one.
This should be done after removing the TB slack, just before adjusting the tension.

On 2000 year model eng (please note that the definition of year model is different between the market), the inner marking (the side facing the gbox) on the cam pulley at the rear exh side is off by 180deg!
Therefore, you must use the marking at the outer face (the one facing the TB rear cover) as that's the only one at the correct timing.
You may be able to use the end/bore scope to look at the outer marking without tilting the eng but you are better off tilting it as it will also help when adjusting the TB tension.


Kaz

 

[goldNSX]

One trick for the TB is to mark the backside of the rear cams as well if you let the engine in the car. This presupposes that the timing was correct so far.

Another trick is to use a mirror and a small camera. A last one would be endoskop.

If you know that the car passes emissions test (the strict one of California) the timing has to be correct. Otherwise HC would be all over the place. Of course, high HC could be everything else but if you test it prior to the TB job and it's low you have a benchmark after the TB job is done. Of course you want to know it earlier...

 

[AcuraNSX]

Everyone has their own way of carrying out the certain procedure and the level of skill/experience are also different.
Therefore, following advices are for those thinking of carrying out the DIY TB service on NSX eng for the first time with limited previous experiences even with other eng and no intension of denying the @AcuraNSX 's method.


Probably you are going to struggle using the holder tool at the rear exh cam while adjusting the TB tension without tilting the engine.

Tilting the eng will provide you with extra room when creating oil free surface at the rear bank #1 cam holder where the rear valve cover sits.
Still, not easy task while keeping the eng inside the bay.....

You don't want tilting the eng while installing the rear valve cover but removing the Eng and Gbox 'side' (R and L) mount bolts will help you during the process.
This will lower the Eng/Gbox assy just several mm yet this tiny amount makes huge difference when it comes to the rear valve cover installation.
Even with this extra tiny space, you are still very likely to be using the 90deg rotated method before aligning the valve cover to the cyl head.
Practice it before fitting the gasket to the cover.
You don't want letting the valve cover gasket touching any of the oily surface or disturbing the area with the liquid gasket applied.

If removing the oil cooler bracket (pedestal), you must clean the mating threads and replace two upper bolts or apply liquid gasket to the upper bolt thread before installation.

Before using the 'marking' method, please triple check that the existing TB is set at the correct timing.
By now, majority of the NSX engine went through its first TB service (although some of the late models in Japan haven't done it yet) and there is no guarantee that the last TB service was done with the TB installed at the correct timing.
Over the years, I saw several mistakes made even at the Honda/Acura dealers.

Please remember that the total number of teeth between the TB and the cam/crank pulleys are different that you only have one chance for relying on the marking.
Once you rotated the crank even for 1 turn, that's it.
The marking won't line up again until you rotate the engine for days….

You can't rely on the 4 x pin punch method on the early 91 engines.
The holes at the holder plate and the cam at the front exh side won't line up when the marking on the cam pulley was aligned against the marking on the cover plate or the top edge of the plate.
This is with the TB removed.
You may be able to insert really thin punch (like 2mm diameter) angled but not with the 5mm one.
If you managed to insert all 4 punches especially the one at the front exh cam on the early 91 engines, you better double check the timing using the markings on the cam pulleys and the crank drive one.
This should be done after removing the TB slack, just before adjusting the tension.

On 2000 year model eng (please note that the definition of year model is different between the market), the inner marking (the side facing the gbox) on the cam pulley at the rear exh side is off by 180deg!
Therefore, you must use the marking at the outer face (the one facing the TB rear cover) as that's the only one at the correct timing.
You may be able to use the end/bore scope to look at the outer marking without tilting the eng but you are better off tilting it as it will also help when adjusting the TB tension.


Kaz

Thank you [MENTION=25737]Kaz-kzukNA1[/MENTION] You truly are one of the very few on this forum that people unequivocally value the opinion of. Your knowledge about our cars is truly impeccable. I am simply in awe of your tremendous knowledge of our cars. I couldn't agree with you more regarding, ASSUMING the first timing belt replacement was done correctly, you can match up old timing belt marks onto your new belt. You would only be repeating the error! I did in fact double check the exact alignment on the camshafts and it perfectly matched up, and the arrow on the oil pump housing with the crankshaft sprocket, when I was at TDC. I even took my straightedge/ruler out just as you did in one of your pics demonstrating this and mine lined up exactly. I ran a compression test and all my readings were between 221 and 237 psi. Question for you [MENTION=25737]Kaz-kzukNA1[/MENTION] , if the timing was off by one tooth, would the psi readings be off by a particular percentage barring all other variances, like piston ring wear, head gasket condition, valve seating properly? How about 2 teeth? And at what point would the interference spelling doom occur? at 3 teeth? 4 teeth? Thanks again Kaz!

 

[Kaz-kzukNA1]

Due to the nature of the VTEC engine and the eng speed during cranking (only about 200rpm), you won't be able to tell the timing issue through the compression data depending on which way (advance/retard) and which side (inlet/exh) the TB jumped the teeth.

Unlike many of the ordinary engines, there is no inlet/exh valve overlap below the VTEC region on our engine.
Another reason why FI application is effective on our NSX.

The cranking speed during the compression check is only about 200rpm through the OBD2 data.

Even the engine with the TB jumped a tooth, it can idle smoothly (again, depending on which way it jumped) and the driver may not be able to spot the issue if mainly driving in the city traffic.

Followings are good example.
These are some of the real data taken by me before making any changes to the engine.
They are all from C30A engine.
The C32B would show higher data.

One of them is the data from the eng with TB jumped a tooth as per photo.

Can you tell which one it is?

[psi]
In the order of #1 , 2, 3,…, #6cyl

A: 224, 218, 223, 220, 215, 228
B: 225, 221, 221, 219, 222, 226
C: 228, 235, 190, 220, 231, 235
D: 227, 230, 236, 228, 226, 240
E: 225, 230, 225, 220, 219, 227

The owner of this NSX with the timing issue didn't notice it for years and while I felt bit of extra vibration at idle rpm, nothing extreme and I didn't spot the issue until after taking the valve cover off for the Eng Refresh.
With this eng, IG timing light at idle rpm didn't show anything abnormal even with 1 tooth off as the idle rpm was fairly stable.

On the other hand, another engine with rear Intake side jumped a tooth in retard direction (if I remembered correctly), showed much more vibration at idle rpm and loss of torque was felt even at city driving condition.

I saw some engines with TB jumped 2 teeth and even heard one engine with just one tooth jump but at 3 different cam pulleys.

While on this subject, please make sure to set the TB tension properly and if you track your NSX, be sure to kick the CL pedal immediately if you spun off.
Even the timing was set correctly at the TB service, it could jump a tooth later if the TB tension was very-very loose and enough reverse torque was suddenly applied.
For example, spun off and reversed the car while in gear without disengaging the CL.
Happened on several NSX in Japan.

By the way, the answer to the above question is data A.

Never tried investigating how far one can jump the teeth before bending the valve.
I have seen 2 teeth jumped at the single cam without bending the valve so at least that's confirmed.


Kaz

 

[goldNSX]

By the way, the answer to the above question is data A.

Thanks for the extended explanation, Kaz. Exceptional as usual.
I looked like it was 'C'.
So we learn that a compression test says nothing about the correct timing if it's only one teeth off.

 

[AcuraNSX]

I would have guessed "C" too. Thinking the dramatic drop in psi on cylinder #3 . Thanks for all the extra info Kaz! So much we can learn from you and other great prime members on this site!