And it looks like the sludgiest milkshakiest nastiest oil in coolant that I've ever seen. Why does the F23A1 do this and is it a crack in the block? Or really just a head gasket?

The first time I've ever seen this was about 6 or 7 years ago when I bought a car for my friend to daily. It had a "blown head gasket" and I figured I could do the work and send my friend on his way. But after 2 head gasket attempts, it still was dumping oil into the coolant.

I just bought another accord that has the same issue. I have never seen any other car with a "blown head gasket" do this this badly. Literally every other honda with a blown HG that I've seen just burns coolant or pressurizes the cooling system.

I'm wondering if this really is a blown head gasket and I'm thinking it's not. I'm thinking it's a crack in the oiling system that allows the coolant to get contaminated.

The only place a blown head gasket could allow oil into the cooling system is in the feed port in the back of the block that passes up through the head. That's the only place the HG seals pressurized oil from the coolant. And to me, that should be extremely easy to seal.

Are these F23A1 engines known for cracking and allowing oil into the coolant?

 

Unfortunately, the F23A1 has a porous block, over time many of the engines develop this issue where the oil is bleeding into the coolant. There is no fix except replacement. it's not a head gasket. Some might come on here and argue, but it's pretty easy (I think) to see the difference. A really blown head gasket will show bubbles in the radiator as the exhaust blows into the coolant passages. You don't have this, you simply have either a crack (possible but I've not seen a crack that's visible yet) or the porous block syndrome that happens. I think it starts to happen on blocks around 165-190,000 miles if it's going to happen. It doesn't happen to all blocks. truly all you can do is replace it. I had the exact same thing. I've seen now the exact same thing on 3 other accords of this vintage, and all were the same. two of them didn't exactly believe me so we tore the engine completely down and could find no blown head gasket nor a crack.

I (and many others) end up buying a replacement engine and throwing it in there. The good thing is this is not an expensive block to find and replace the whole thing. In my case, I bought a JDM block which comes from Japan because 1- it has about 50,000 miles on and 2 - my hope is the Japanese block might not have the issue (I really haven't been able to confirm or deny if there is any merit in that hope). This way, you can go another 100,000 mile easily before it might happen again, maybe 130,000. It's really not *that( hard if you are mechanically inclined. I wrote up roughtly what it takes to do it, but also several others have as well, you can decide what to do.

Here's one persons walkthrough:

https://honda-tech.com/forums/honda-...-auto-3328540/

and here's mine, quite similar:

https://honda-tech.com/forums/honda-...thers-3345715/

replacement JDM with about 50-60k miles on it.
https://www.ebay.com/itm/HONDA-ACCOR...YAAOSwkcFbGC2X

Good luck with your decision. Many of us have been there.

 

thanks for the response. I do have another good F23A1 on hand that I'm going to swap into this accord, I've done the swap before so I'm not too worried about it.

I was just curious and wanted to confirm that it wasn't just me that was getting this issue and that indeed a head gasket job wouldn't fix it.

 

Yep, I would not waste time with anything other than junking that engine. I sold my old engine to someone who needed heads, so I sold it for $50 if he would take the whole engine. Also gave him all the JDM stuff because he wanted to play with it (mine came with things like the JDM alternator, which I had no use for, the exhaust, intake, injectors etc. In my case I also bought a whole replacement transmission so I could pull everything out and refresh it with about a 50k mile motor and trans. Nothing was wrong with the trans, I just figured I would scoop everything up since I was in there.

With the engine out, other things (which I think I made note of) was anything else that might be a pain to do is easy with the engine out. So things like motor mounts, steering racks, new hoses, brake lines, etc. I also re-gasketed parts of the engine like oil pain, valve covers, new timing belt, etc to complete the refresh.

Sucks but at least it's not a $10,000 BMW replacement motor

 

hahaha funny you said BMW motor. My friend literally told me today that he wants to buy a 2000 323i with this exact issue. Oil in the coolant and it's milkshaked bad. I told him that it's most likely a cracked block and that a head gasket job won't fix it. We'll see what he decides to do. He's pretty set on buying it tomorrow.