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What is the problem with the engine?

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1988 Honda Prelude 4ws B20A7
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Discussion Starter · #1 ·
Hi, I'm Rafael from Portugal and I bought a stock '88 Honda Prelude 4WS with 150hp as my first car, 2 years ago, and I'm here cause after 2 years and a full body restoration, I broke the car.
I had been going at 200KPH (125MPH) for a while, then I eased up a little bit, and to around 150KPH (95MPH) for 15 minutes, and in hindsight, the car wasn't sounding like usual and it wasn't accelerating as usual, but at the time I thought it was just my head screwing with me. Finally, I tucked in behind a car and gave it gas to keep up in the slipstream and immediately lost power and started steaming everywhere. Stopped on the spot, turned off the car, opened the hood, and water was pouring out from the coolant expansion reservoir and steam from the radiator. There were some pieces of something black that looked like rubber but felt like foam on the underside of the cap. Then I went and fired up the car just to ease my mind and it took some second for it to start, and when it started the engine was vibrating violently and sounded awful.

I think the pieces of black rubber are from a coolant line seal/oring, clogged up the radiator and the pressure made something erupt and the water pump stopped turning from the heat or pressure buildup. The timing belt spun because of it and now the cams are off timing making the car have a really rough idle.

Oil temperature was perfect and there was no steam before the massive power drop.

Motor Shaking and Sound

Tell me what you think has happened
 

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1988 Honda Prelude 4ws B20A7
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Discussion Starter · #6 ·
How do you know the cam timing is off? have you checked? have you done a compression test?
I haven't, I don't even have the car with me yet, should arrive on friday, just thinking about possible scenarios.
Can an off-timing engine even cause the vibration?
A blown head gasket was the first thing to come into my mind when opened the hood, can't understand why I ruled it out tbh.
 

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I haven't, I don't even have the car with me yet, should arrive on friday, just thinking about possible scenarios.
Can an off-timing engine even cause the vibration?
A blown head gasket was the first thing to come into my mind when opened the hood, can't understand why I ruled it out tbh.
OK, so I would do a compression test first and go from there.....
 

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1988 Honda Prelude 4ws B20A7
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Discussion Starter · #9 ·
This can happen if you have a blown head gasket between a cylinder and a coolant passage. Do a head gasket leak test.
I would do it when I get the car, and a blown head gasket is probably one of the problems, but last time I started it the engine was vibrating so violently that the whole car was shaking. I doubt a passage from the coolant to a cylinder can cause such vibration, so I probably have one more problem.
 

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1985 Prelude
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I would do it when I get the car, and a blown head gasket is probably one of the problems, but last time I started it the engine was vibrating so violently that the whole car was shaking. I doubt a passage from the coolant to a cylinder can cause such vibration, so I probably have one more problem.
Your head gasket could be blown multiple ways. Do a head gasket leak test and a compression test. I looked at the video you posted and, frankly your engine sounds like the engine on Lucy, one of my project cars. (The engine on Lucy turned out to have low compression on 3&4, which is typically caused by a blown head gasket between the cylinders, though a full diagnosis is pending.) Tests are cheap, parts are expensive, do the tests.
 

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Discussion Starter · #11 ·
Your head gasket could be blown multiple ways. Do a head gasket leak test and a compression test. I looked at the video you posted and, frankly your engine sounds like the engine on Lucy, one of my project cars. (The engine on Lucy turned out to have low compression on 3&4, which is typically caused by a blown head gasket between the cylinders, though a full diagnosis is pending.) Tests are cheap, parts are expensive, do the tests.
Sounds like I got a Lucy too, it explains a lot of what was happening.
I think i'll only do the compression test tho, turning the engine on for a head gasket test sounds like a recipe for disaster cause of engine knock.
 

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Discussion Starter · #13 ·
Are you sure you did not punch a hole in the block?
Pretty sure, as you can see on the video the car run for about 15 seconds, before I stopped I was doing 160k/h on the highway, and the only puddle on the ground was from water on the front right corner (where the coolant expansion reservoir is) and no trail left behind the car.
 

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Discussion Starter · #14 ·
Update: I've got a hole the size of an orange on the block, and at least 1 bent connecting rod.

The shop gave me 2 options, either get another B20A7, tear it down and replace the seals, gaskets, etc., or get a new block+crankshaft, use all the parts that are still good from the broken engine and buy the rest.

I've read in many places that the B20A engine family (3rd gen preludes only) uses the same blocks, but nobody seemed to be quite sure. Is this true on not?
What are my realistic options? I can't find a B20A7 for sale online, much less just a block and crankshaft laying around.
 

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Damage like that means the engine is completely trashed. Don't waste the effort trying to salvage a part from an engine that threw a rod. I do see the engine listed on car-part.com at some junkyards, but you'd have to call junkyards until you find one with your engine, get a quote, and have it shipped to you. What's your budget?
 
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