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Restoration/Revival Project ('93 Prelude 4WS)

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2 small updates on the project. Firstly, I ordered some Powerstop front pads and rotors. According to the service records, the front rotors are from 2008. And I warped them recently doing a quick slow down from 70 mph. That should get her fixed up nice again.

Secondly I have scheduled a dyno day on June 10th. I know, crazy right? This day was actually intended for my 2g but it will not be ready. This was a group buy and we have the shop rented for an entire day so I still wanted to show up with something. It will be interesting to see what a mostly stock 31 year old Honda engine puts out. I may take some wrenches and see if we can get the ignition timing dialed in a little bit to snag some extra power.
 
Ahhh. I remember that car well. Was working at Dobbs Honda in Tucson in '93. Back when Honda only produced 3 models - Civic, Accord, and Prelude. They had just come out with the Pilot; they were testing the waters. The first year the Pilots came with an Isuzu engine. I remember opening the hood on a new Pilot and was like, "what the hell is THAT doing there?!"

I preferred the Civics then, because I made more money on them. Civics didn't come with A/C and I got paid 4 hrs to install A/C systems in them. Got it down to about an hour.
 
Currently at the shop and just finished my dyno session. She threw down 211 torque at the wheels. That surpassed my expectations and I'm satisfied for a 31 year old engine that's never been opened up. I'm working on editing the video later tonight and will post it. She started letting some smoke out in the higher rpm range and I believe it's the old valve seals.
 
We did 3 pulls and the numbers were rising each time. The 1st pull she was still cold and at base ignition timing. 3rd pull she was hot and dialed in. This car sounds insane to still have a stock exhaust system besides a test pipe.

There was also a K series Civic running. He made good power but didn't touch my torque.

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We did 3 pulls and the numbers were rising each time. The 1st pull she was still cold and at base ignition timing. 3rd pull she was hot and dialed in. This car sounds insane to still have a stock exhaust system besides a test pipe.

There was also a K series Civic running. He made good power but didn't touch my torque.

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That’s pretty awesome, not gonna lie. I hate those civics and always enjoy taking them to gapplebees so I love that the 30 year old grandpa beat it in torque. Lol.
 
It's sooo tempting to tear this thing apart and rebuild it to make 250ish hp & 300+ tq NA. But I'm probably just going to leave it OEM plus. This type of car would make for an awesome weekend toy though. The instant torque delivery makes it fun to cruise around in and the suspension setup handles amazing. If I ever have the extra cash I'll run across a beat up Prelude to build. Would be a shame to mess this one up. The original owner's father would probably roll over in his grave if I did ROFL
 
It's sooo tempting to tear this thing apart and rebuild it to make 250ish hp & 300+ tq NA. But I'm probably just going to leave it OEM plus. This type of car would make for an awesome weekend toy though. The instant torque delivery makes it fun to cruise around in and the suspension setup handles amazing. If I ever have the extra cash I'll run across a beat up Prelude to build. Would be a shame to mess this one up. The original owner's father would probably roll over in his grave if I did ROFL


I learned(eventually) never to mod a reliable daily past basic stuff. Just never a good idea.

Definitely grab another one and go full racetard though. If your ears can handle an NA Honda that is. :p
 
I noticed the radiator started leaking around the upper plastic tank. It's only a year old. This is not the first time I've had issues with plastic tank radiators over the past few years. Brand does not seem to matter. I absolutely hate them. This is why when I originally ordered the radiator for this car it was a Mishimoto full aluminum, but they refunded my money next day and said no more were in stock. I guess I'll contact them now and see if they have any more or plan to.
 
I replaced the clutch master cylinder today. I started getting a squeaky pedal and noticed the interior rod was wet. Luckily no fluid reached the carpet. Glad to have another 31 year old part swapped for something new. My vacuum bleeder made easy work of getting the air out and fresh fluid in. It would be painful to bleed this system manually since the lines are a mile long, though I ran through a few cycles after vacuum bleeding just to be sure. It looks like I definitely needed the fluid changed out. Even after replacing the slave cylinder last year some contamination was left behind. A lot of this was trash in the bottom of the reservoir, I made sure to thoroughly clean it out while removed. You'll also notice a handful of nesting material. There were about 4 handfuls of it from where a rodent was previously hanging out in the master cylinder area. Better on the outside of the car than the inside. I guess I'm lucky it didn't chew up any wires and such. Typical for vehicles that sit a while.

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Hey - you might want to check under the dash where the pedals afix to the firewall. I've had a few Civics of that era where the clutch pedal gave way because the spot welds in the plate gave up the ghost. The attachment plate was thin steel. Doubt you'll have issues as I think the preludes were made with stouter materials... but worth the inspection.
 
Hey - you might want to check under the dash where the pedals afix to the firewall. I've had a few Civics of that era where the clutch pedal gave way because the spot welds in the plate gave up the ghost. The attachment plate was thin steel. Doubt you'll have issues as I think the preludes were made with stouter materials... but worth the inspection.

I've been under there a few times. It's surprising how immaculate the interior is. Not even a spec of rust under there, which is usually a problem with older Hondas. I even found my chime control/valet mode panel still in tact.
 
Decided to stop by the junkyard and check out a 1995 Prelude they had. It was already mostly torn apart and had been wrecked so there weren't many usable parts. I did get something I needed though. Driver tail light sockets and pigtails. My only dash warning light that has been on (intermittently) is the brake light indicator because of loose connections. It's honestly easier to swap the whole panel than to replace a single socket or connector. I will store mine somewhere for spare parts.

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I was able to get my hands on an all aluminum radiator. It was seemingly impossible to get one from Mishimoto so I went with Yonaka Motorsports. It seems like a nice unit. Some of the welds are slightly uneven, but that's to be expected with a human fabricator instead of machine. Overall it's a nice looking and feeling unit and I can't wait to install it. This model does have bolt holes to retain the OEM fans. I'm currently undecided on which fans to use. I will hook up one of the Yonaka fans and see how much air it pushes compared to an OEM fan. If it's similar or better then I will use their fans, if it feels weak I will just retain stock fans. I'm waiting on some new OEM radiator bushings to arrive before I install. I also plan to pick up some Type II coolant, since that is recommended by Honda service manual. Will be nice to have peace of mind that my radiator isn't falling apart after one year haha.

They also sent me a pretty nice T-shirt that I may actually wear. I usually don't wear the promotional/advertising clothing, but this one is quite nice.

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The radiator bushings arrived so I made time to install the radiator. First I tested the Yonaka fans and am impressed. I was expecting to use the OEM fans but these seem to move just as much air if not more. I wasn't on board with their instructions of cutting the connectors off the wiring harness so I soldered the OEM fan connectors on the Yonaka fans for removability and as close to stock fitment as possible. Also added some plastic wiring conduit that I had left over from making my 2g wiring harness to cover up the soldered area. The only issue I've had is having to shave down the drain petcock a little bit; it was so long it contacted the subframe haha. Once that was shaved everything fits properly and the temp stayed pretty low on a test drive.

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For the first time, it left me stranded on the side of the road. I got it trailered home and parked in the garage. Waiting to be diagnosed. I believe it may have jumped timing. While cruising on the highway it started running very rough and died as I pulled over. Try to start it, spins slow and shoots fire from tailpipe. I won't know much until I rotate the engine by hand and check the timing marks. I don't think valves are smashed because I never felt or heard anything to indicate that. The belt tensioner has probably weakened and allowed timing to jump 1 or 2 teeth, was able to stop running before mass destruction. That's my hope anyway. We'll look and see in the next few days. I went ahead and ordered the full timing kit. My collection of service records indicate that the belt and tensioner were last replaced in 2011. I know, should have already replaced it in my ownership. I was putting it off until I had time to completely rebuild the head since those jobs are hand in hand.

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I made some very interesting discoveries while tearing the engine down. A jump in timing was the correct assumption. But the cause, I never would have guessed. The lock bolt for the mechanical tensioner had completely fallen out. The only explanation I can come up with is that the bolt was not properly torqued in 2011 when the tensioner was installed. The car was stationary from 2015 to 2022 so I suppose that prolonged the fate of the failure and belt damage. It's strange to see such an error on a job that was done at a Honda dealership, using all OE parts by a certified technician. But who knows, maybe it was rushed on a Friday evening LOL .

TECHNICALLY the labor/workmanship is warranted for 60k miles. The car hasn't reached half of that. But I always do my own work, and I already purchased new parts before realizing this. I'm not even sure if this dealership is still operating either. Better to just do it right myself.

I have read just about everything I can find in the manuals and technical documents and it seems no thread lockers are to be used on this bolt. It is written that it should simply be torqued to 22 ft/lbs. I was hoping that maybe someone had just forgotten to use threadlocker, or at least that Honda would recommend use thereof to cover their ass. But no cigar. Either way, my torque wrench is calibrated and I'm sure a dot of Loctite will not hurt. To prevent this in the future.

I also found that one of the balance shaft seals was leaking. So it was time to tear it open for maintenance anyway.

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I have some good news, and some more strange news. The good news is that none of the cylinder head is damaged and valves are not bent. It does not appear that the timing jumped far enough to cause piston interference. Some fresh belts, pulleys and seals should have that side of the engine back in order.

But let's move on to the other side of the engine and reveal this strange news... As you may know, the distributor on these engines are driven by the exhaust camshaft. When I unbolted the distributor cap, pieces of plastic fell everywhere. The rotor had completely fallen apart. It's only been a few months since I installed this rotor. I can assume it had been sitting on a shelf for a few years with how brittle it is.

To have the distributor rotor decintigrate and the timing belt get chewed up at the same time seems like a rap of bad luck. Maybe I can make sense of it though. I suppose if the exhaust cam jumped timing, that sudden jolt of energy caused the rotor to break apart. An unfortunate series of events that would be. Either way, I've found everything necessary to get er fixed. It should be running nice and smooth after it's all put back together. I also decided to install some fresh plugs during assembly. Even though it's only been a year, I decided why not since I'm already in there. I typically don't reuse spark plugs.

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That seems sensible, we'll roll with it LOL . I'm just ready to have this thing back on the road. I've been daily driving an '01 Accord F23 with auto trans for the past week. It's a great car but floats like an old Cadillac and granny shifts. I'm ready to be back in a car that hugs the road and shift through some gears. I've been told countless times to keep miles off the Prelude, but where's the fun in that?
 
Got everything put back together today. Runs great and extremely quiet. I put 20 miles on it and do not see any leaks. I hung the engine on a new mount since this one was still the original. And had an unusual amount of corrosion. Almost as if brake fluid had been spilled on it in the past, though the strut tower has no corrosion.


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She gave me 2 weeks of hardly being used before deciding to cost me more money. I've been smelling coolant when I turn on AC/heat for at least a year. But never been able to find the cause. Had thoughts about a heater core leaking but coolant was rarely low and not enough to worry about. Well the issue showed itself tonight. Noticed some coolant flavored steam while entering the neighborhood from getting groceries. Coolant on the downpipe. Diagnosis was quick since coolant was actively seeping out of the headgasket while I looked. It did not run hot, I turned it off in time. I drained the oil (which was painful being so fresh) and there is no coolant contamination at all. The compression results are good with only an 8% variation highest-lowest. It's similar to a headgasket issue you'd see with a Toyota 2GR engine. Spews coolant but will not cause internal engine damage unless you run it hot or let the issue worsen.

There's a bright side to the situation. All those little hoses and gaskets that I haven't gotten to as regular maintenance will now be replaced. Everything freshened up and tidied up.

The downside is that I get to look at the car sit for too long. I'm sure it will be a 2 week turn around to have the head reconditioned this time of year.

I can't really say I'm surprised that a 31 year old engine is having a headgasket issue. But the mileage just isn't there. I was going to try and reach 200k, or even 175k, before touching any internals but I suppose that won't happen at all.

I'm definitely curious to see exactly what went wrong with the headgasket. It's the factory MLS gasket so I wouldn't expect it to deteriorate like the composite ones do. We will see though.
 
Earlier I mentioned that the car was smoking a bit on the dyno and I assumed it was the valve seals. That was the correct assumption. The exhaust ports are filthy and you can see oil on the valve stems. This head is getting thoroughly hot tanked and rebuilt. I'm on the fence about replacing the valves. I guess I should remove them and check for wear but they don't look so great. I also spotted a couple problematic areas on the headgasket. I removed it as gently as I could given the situation. Don't see any rubberized coating remains on the head or block surface so this was existing damage.

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