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Okay, I have a question about this head I've had for 3 years now that seems to love leaking coolant into cylinder 2. The back story is, I had a running engine. Life was grand. Just a stock bp4w. I dreamt of a turbo. I found someone locally that said they would build a bp4w for me with OEM seals and gaskets, coolant reroute, upgraded rods, etc. Fast forward about 6 months. The engine is in, I'm buying turbo parts, I have a 6 speed swapped in and megasquirt is online running the motor. I was excited. The only problem was that the car had a dead miss on cold starts, and there would be some white smoke / steam out of the exhaust on hot starts some times. No big deal I thought. I had the engine builder look over the engine. He sent me a video of cylinder 2 having coolant come into the cylinder when it was under pressure and he was looking into the bore with a borescope. The entire cylinder was super clean compared to other cylinders. Anyways the spark plug snapped the threads off in the head so it needed to be pulled. I pulled the head off and sent it to the machine shop to have it decked. Once back in my possession, I cleaned the block as best I could and installed my refreshed head. We went to dyno tune the car and everything was great.
I started daily driving the car to work (100 mile round trip). Eventually the dead miss comes back, and using coolant. Keep driving. Decide to turbo the car. Everything is grand again. Really fun. Datalogging a lot. After about 2 weeks, during a log, I feel a slight hiccup at the top of 4th gear. Like a tiny loss of power that goes away instantly. Go home that morning and park. The next day, I go to start the car and what do you know, I am dumping coolant out of the exhaust. I pull the head off again. Cylinder 2 has decided to puke coolant into the cylinder. This time, it was extreme. The car would barely start and once it did, it was just a steam show. I'm assuming this is the same failure point as the first head gasket the engine builder installed. But why? I can't find any issues with the head. I told the machine shop to look over for cracks and they said they couldn't find any. The block seems to be fine. The cylinder walls on all cylinders look great. No scoring or marking. The only thing I can see is that maybe this small pocket in the exact area the video I saw of coolant entering the cylinder is located. What do you guys make of it? Should I scrap the head? Machine it down to this? Its maybe .015" at its deepest.
I really need advice because I work full time 50 miles away and I am in college as well and this is my daily. I'm getting so frustrated with this motor I want to just buy a stock BP4W and stop pulling off the head. I have attached some photos here.
Here is what I first saw when I removed the manifold.
After disassembly, I really can only see this as a possible cause? This is on the head on the offending cylinder, on the side of the cylinder we saw coolant seeping through ever so slightly before I did the head gasket.
Showing with the gasket a little bit away from the head.
Now here with it pushed up a little bit closer just for ***** and gigs.
Probably be more questions than these. Clean head and get a straight edge and report back. Also straight edge the block.
what brand head gasket?
ARP studs or head bolts? What torque?
Did you get to do a leak down before the head came off either time?
just trying to think of stuff that might be a clue
Probably be more questions than these. Clean head and get a straight edge and report back. Also straight edge the block.
what brand head gasket?
ARP studs or head bolts? What torque?
Did you get to do a leak down before the head came off either time?
just trying to think of stuff that might be a clue
Hi sorry for lack of info.
Straight edge block and head with Starrett straight edge. Minimal low spots .001" here or there on the head. Block is straight straight.
ARP studs, torqued to 60 ft-lbs. Checked 2 weeks ago. Before that never checked. Re-torqued them in stages to 60 again. One or two moved 1/32 of a turn on the intake side.
No leak down test. First time I pulled head off it had no compression cold on cyl 2 and 4 due to loss of valve clearance (valves ate the faces off on the valve seats due to bad springs or bad cuts? Replaced valve train when it was in the machine shop). The car like 2-3 days ago was pulling 21-22inHg of vacuum once warmed up. Cold was maybe 10-15 with a dead cylinder (guessing 2 due to water?)
Okay, update today from machine shop after pressure testing the cylinder head. They found 2 pinholes in cylinder 2, one between the valve seats and one on one of the cooling passages near the exhaust side. This would explain why I kept getting coolant in the cylinder. Looking to source a head locally for now.
I have sourced a head, sent it to the machine shop, and reinstalled it back on the block. The car started up fine first go around. Test drove a few miles and didn't see any leaks or issues. I have driven it to work tonight (~50 miles) and haven't seen any issues either. Hoping that bad head was the cause of all the misfires and weird events that kept happening.
I had the machine shop install the Volvo valve springs to do some reliability testing of my own. I sourced them from a website called midwest miata parts for around $80. Hopefully the car lasts!
10-22-2023, 04:47 PM
BP4W keeps popping head gaskets. HELP ME PLEASE
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