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Discussion Starter #1
Hi, I recently acquired Duckeedoug's 1991 Prelude blue Si. He was extremely meticulous with the car's upkeep, and the overall body and interior looked fantastic for being almost 30 years old. Alas, he had two engine failures during his ownership, and decided to offload it.

I'm originally from Northern California (Oakland), and my family and I moved out here to the Boston Metro a little over two years ago. 3G preludes do not exist here as the New England winters and salty are just punishing. I still peruse California Craigslist, and that's how I came across Doug's car. My sister and I had a '85 Prelude back in high school, so picking this car up helps quell that nostalgic factor.

The current engine in the Prelude is a hybridize B20A3 with a PK3 head. The head gasket ultimately failed, and I was told it wasn't from overheating. If that's the case, I suspect the wrong head gasket was used (B20 instead of B21). I had originally wanted to just get a shop to replace the head gasket, but with FSMs and YouTube at hand, i think I should be able to replace the head gasket myself. OEM head gaskets are long gone, so I'll have to look around for a quality OEM-equivalent variant.

I have been combing and absorbing a lot of information in these forums, and hope to contribute once I get more familiar with my car. Thanks.
 

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I can sell you the Cometic B21a1 MLS headgasket if you want to get the best HG on the market now. I invested into the project in 2012 and got it done.

You should be able to search Cometic MLS headgasket for the B20a5 and B21a1's.
 

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New England does make it hard for upkeep as the salt they use on the roads are the kryptonite. I'm from Connecticut and keep an eye on Craigslist all over new England which is where I've practically gotten the 3 I've owned. (1. 1990 si 4ws 2.1l. Daily driver 2. 1991 2.0si sold to a friend. 3. 1990 2.1lsi 4ws parts car.) Keep an eye out...there are very few of them in this area but we do exist!
 

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Discussion Starter #5
Wow, you dug deep to find those out here. Crazy that you are dailying that. Do you put the underbody corrosion coating on there?

One thing I noticed is that a number of the mechanics shops here won't touch older cars. Maybe it was the hybrid engine combo I told them, but as soon as I told them "1991" head gasket" they wouldn't even touch it with an ugly stick.

As for tires, I have only come across some Falken Azenis for the stock tire size. Were there any other sizes available that were performance-oriented?

Finally, I have read that the B20A3 crank bearings were smaller than those on the B20A5. From an engine longevity perspective, should I baby the engine?
 

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Would an MLS gasket be overkill for an otherwise OEM engine with stock horsepower?
Not if you are looking for the best headgasket on the market for the Bastard B motors. Other than that, you have to use the FelPro or Evergreen brands as those are the only brands left.
 

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Wow, you dug deep to find those out here. Crazy that you are dailying that. Do you put the underbody corrosion coating on there?

One thing I noticed is that a number of the mechanics shops here won't touch older cars. Maybe it was the hybrid engine combo I told them, but as soon as I told them "1991" head gasket" they wouldn't even touch it with an ugly stick.

As for tires, I have only come across some Falken Azenis for the stock tire size. Were there any other sizes available that were performance-oriented?

Finally, I have read that the B20A3 crank bearings were smaller than those on the B20A5. From an engine longevity perspective, should I baby the engine?
Yea I definitely have done some digging. By my daily driver I wasn't clear but I park it for the November to march months. I do plan on coating the under carriage. I've been slowly refurbishing the entire car but I like to pile up all the spare pieces I can. I haven't had much of an issue with mechanics in CT but I also bring my own parts and I do my own work except big projects. Couple Honda fests in new England also..keep an eye out people go crazy when they see 3rd gens pop up.
 

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Discussion Starter #8
Since you guys seem more knowledgeable on the 3rd Gens than me, do you recommend that I do a compression test prior to tearing down the engine? Since I am already replacing the head gasket, I wonder what benefits do I get out of this. I am planning on checking the head bolts torque as well as the head gasket itself to see what the root cause was.

I go to Cars and Coffee and Radwood, but didn't know there were Honda Fests out here.
 

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Since you guys seem more knowledgeable on the 3rd Gens than me, do you recommend that I do a compression test prior to tearing down the engine? Since I am already replacing the head gasket, I wonder what benefits do I get out of this. I am planning on checking the head bolts torque as well as the head gasket itself to see what the root cause was.

I go to Cars and Coffee and Radwood, but didn't know there were Honda Fests out here.
It's never a bad idea to get a hint at where issues may be or where they may have started. I'm still learning alot myself. It is best to torque everything to spec as everything seems to run smoothly that way.
They do have a Honda day...weekend thing...in Jersey or Maryland I believe? It changes you would have to look up for this year. They also do a Honda fest at Thompson speedway in CT around June sometime. Hoping to make it this year.
 

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as I told them "1991" head gasket" they wouldn't even touch it with an ugly stick.


Finally, I have read that the B20A3 crank bearings were smaller than those on the B20A5. From an engine longevity perspective, should I baby the engine?
It's odd that they wouldn't want to do the head gasket. It's not a hard car to work on. If you do it right, you don't have to remove the crank pulley, lower cover or either manifold from the car. You undo everything around the head, then pull the head. (If it's time to do a timing belt and water pump you might as well pull the lower timing cover and crank pulley.)

The A3 was the carbureted engine. If memory serves, the bearing journals were smaller than the B20A, A5 and B21A1. Longevity shouldn't be a factor but you probably don't want to try and make 300HP with that engine. :D
 

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Discussion Starter #11
Good to know. I'll probably follow what's written in the FSMs, but will definitely try and see if I can pull the whole head part of the engine out without having to remove so many other sub-assemblies. No, the timing belt is still good, about 10k miles on it, if even. LIke I said, the previous owner unfortunately spent a lot of time with engine-related issues.

Also good to know that this engine isn't "fragile." I had read a few posts from concerned owners cautioning redlining this car. I had always thought Hondas were built to rev, and so these warnings put a damper on the car.

The replacement plan will be the a head gasket replacement kit and an MLS head gasket to use instead of the one found in the "kit." Also plans to do a compression test and check for flatness before tearing / putting things apart / together. Just waiting for some warmer weather.
 

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Discussion Starter #12
I have actually been trying to get a hold of Sean (1funryd) to see if he can price match on the cometic head gasket, but have not been able to get a hold of him.

Also, not to sound cheap, but how.l crucial would it be to replace the other seals and gaskets (cams, intake/exhaust manifold) if they’re not leaking initially?, and hv about 10k miles on them per previous owner?
Thanks
 

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Discussion Starter #14
Ah, I failed to expand your full signature. I was in the forum's "start a conversation" feature, thinking it was a "private message" type of thing. I had ping'd you a few times using that feature; I guess that feature doesn't work that well.

I don't frequent facebook, and I was emailing an old email address from your website (@q.com?)
 

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Discussion Starter #15
I had a chance to do a compressions test on the cold engine: 75psi, 75psi, 25psi, 175psi. I didn't get a chance to add oil into the cylinder to see if the piston rings were shot, but seeing that the engine oil was light brown was basically a telltale sign.

I also noticed a lot of white deposits in the coolant. Not metal flakes, as they dissolve as I rub them. I'm hoping the previous owner just had a case of high-calcium content tap water put into the cooling system.
 

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I had a chance to do a compressions test on the cold engine: 75psi, 75psi, 25psi, 175psi. I didn't get a chance to add oil into the cylinder to see if the piston rings were shot, but seeing that the engine oil was light brown was basically a telltale sign.

I also noticed a lot of white deposits in the coolant. Not metal flakes, as they dissolve as I rub them. I'm hoping the previous owner just had a case of high-calcium content tap water put into the cooling system.
Dem some low numbers.

Average B20/21 compression numbers are: 165-200psi
 

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Discussion Starter #17
Yes sir, the differences really point towards a bad had gasket. Worn piston rings would have smaller pressure deltas.

I have searched the forums and saw a couple of posts from member Dano mentioning this, but I wanted to get some confirmation that the power steering TENSIONER PULLEY BOLT (the 14mm hard-to-reach-faces-streetside bolt) is a regular thread (not reverse thread), correct? Mine is not budging, and I have went both directions. I had to take a break from trying to loosen that bolt as it was becoming pretty frustrating.

Going to jack the engine up a bit to get better bolt head engagement and put pipe extension, but someone please confirm. Thanks.
 

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Discussion Starter #18
I just realized I don't have to store pictures onto the cloud to share onto here.
Here it is getting towed onto the trailer for the ride across the country.

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The previous owners took really good care of the car, and it shows.

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As mentioned, the car seems to have a blown head gasket, and this is how it sits as I chip at it when time / weather permits.

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I don't consider this thread so much a "build," as I'm just trying to repair / replace and get it back on the road. However, if the moderators feel it belongs in the "builds" section, feel free to move it over there.
 

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Discussion Starter #20
Unfortunately the tensioner pulley nut is too stripped. Even fancy box wrenches won't get a good grip. I have, since then, PB Blasted it and might either try chiseling it or give the box wrench another shot, but at this point it seems grim.

I have read that you can just remove the power steering pump off and pop the belt off. I understand it might not be the most proper way, but at this point I'm stuck.

I have also read about removing the bracket for which this pulley mounts onto, maybe somebody provide insight on this?

Thanks in advance.
 
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