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loungin112

Another smoking L20b

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Greetings...

 

I tried searching for this issue without any success.  My situation is a bit different than everything I have read, so I'm hoping the gurus here can give me direction.

 

I have an L20b (likely from a 200sx due to the dogleg that is with it) that went through an entire, overpriced and drama-filled, rebuild in 09/2016.  I wouldn't trust the builder with flushing a turd, so bringing the car/engine back to him is not an option.  With that said, there is virtually 0 miles on the rebuild since I have been working on other things to get the car ready to drive.  So, here is the problem:  after the first freeze (not really that cold though) of the year, I noticed a pool of antifreeze under the car.  I searched for the source and could only find a small pinhole in the exhaust collector which is where the antifreeze was coming from.  There was perhaps 1/2 to 3/4 cup worth on the floor.  I held my breath, started the car, and a bunch of moisture spurted out the back.  Then came the white smoke.  Not a lot (perhaps extended one foot out tail pipe) but is spitted a bunch of fluid.  There was some oil mixed in there too...i imagine from the new rings still settling.  The radiator emptied quickly.  

 

So, I tried retorquing the head bolts.  Same result upon startup.  The head gasket is the 1.5mm nismo with new head bolts, part # listed in the DQ.

 

I'm' stumped due to the newness of the headgasket, the mixing of oil/antifreeze, and the small amount of smoke but huge amount of moisture.

 

My next step is to recheck the intake/exhaust manifold bolts, but they look okay as of now.  Oh, and I forgot to mention that prior to the first freeze, the engine ran like a champ...smooth, a little rich, no pings/knocks, etc.  Some oil exiting the exhaust but no moisture or smoke.  

 

Thanks everyone.

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Send head to machine shop to test for leaks.

 

Replace head gasket while doing so.

 

You'll probably find something obvious upon disassembly.

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I should add the following:

 

dual 38mm SU's

Stock Exhaust mani

U67 head

p68 pistons

AmeriCam

Mallory distributor

Stock radiator

 

Regarding the mechanic...seems to be a good mechanic but a crook.

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Send head to machine shop to test for leaks.

 

Replace head gasket while doing so.

 

You'll probably find something obvious upon disassembly.

 

Thanks...I guess it could be worse.  Thanks for the suggestion.

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Dogleg does not guarantee engine is from an S10200sx....could also be from an A10. Could be from 620, 720, 610 or 710 also. After all these years things get traded around a lot to keep them on the road.

 

If you have the proper antifreeze/coolant you shouldn't worry about any freezing. You do have antifreeze in it?.

 

 

 

 

 If U67 head what intake did you use? and did you drill out the two holes in the head to allow coolant to flow into the intake runners?

 

 

A few things. You said you don't trust your mechanic/rebuilder?

 

Head is severely warped to have an external coolant leak on the manifold side.

Head to block alignment dowel(s) were lost/not used and head is on crooked and gasket not sealing properly.

Head/block surfaces not cleaned of old gasket properly, new gasket not sealing.

 

Intake exhaust gasket is not clamped properly and the two coolant runners in the intake manifold are leaking. 

 

The steamy exhaust is likely normal. All engines have steamy exhaust in the winter. If you have antifreeze in the coolant, smell the exhaust. If there is coolant present it will smell sweet. This could be the intake sucking in coolant at the gasket when running, leaking on floor when not.

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White smoke is normal during cold mornings. You can do a compression check.

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Leaky intake/exhaust manifold gasket? Check the torque on those fasteners first, then remove the intake if it persists.

 

Did you install the intake? Did you surface the manifold with a Roloc disc on a 20000 rpm grinder? If so, that's bad and could be the cause.

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The big question: where did the coolant leak from? How did the radiator empty so quickly?  

Napa sells a "Block Tester" that allows you to pressurize the cooling system to see where the coolant is going.  Good investment.

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Thanks for the insights and direction.

 

Mike, i agree, the trans could be from any of those models you noted....assumption on my part...the car was purchased from someone who didn't care about the car history. And, i don't know about drilling out the intake.

 

I'll start with trying to tighten the intake and exhaust manifolds...hopefully that is a cure. Otherwise, of comes the head for a pressure test.

 

Stoff...i do not think the head was cleaned up in the manner you noted. But then again, reference my earlier comments about the mechanic/rebuilder.

 

Distributorguy...thanks for the suggestion...i may need to add to the tool chest.

 

Question: if the head was installed without the alignment dowels, would such an issue result? Are the dowels a port or channel for coolant or simply an alignment mechanism?

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Two of the head bolt holes in the block (on the left side) and the head have a wider hole. A small sleeve or dowel fits into the block holes and sticks up. When the head is aligned it drops down over the dowels

 

fel-es74007_w_ml.jpg

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Overdue for an update.

 

I tried tightening the intake/exhaust manifolds. They were a bit loose and could be toughened a bit, so i did. No difference...still spitting like my 9th grade math teacher. Coolant spraying everywhere out the exhaust. No plume of smoke though.

 

Pulled the carbs and intake manifolds of last night. Crystallized coolant in the intake manifold. Weird. No, the coolant ports are not drilled on either the mani or head. No cracks seen on intake mani.

 

Next up, removing the exhaust mani and then the head.

 

Suggestions welcome. Still very weird as to why coolant would be in the intake mani, not burn, but would spit out in high volumes. Hoping it's not a cracked block.

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explain if no water passage on carb manifold then it shouldn't leak(as you not running a water line to the carbs.(should plug that out let by the fuel pump.

 

But you said you have SUs and the manifold have water passage holes unless they plugged up. so this story is not clear.

 

if head is not drilled(no water passage ) then a water line to the SSS manifold is not needed)

 

your leaking/Sucking in water elsewhere

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Massive head gasket leak could result in coolant coming up the intake passage into the manifold. Would explain a lot of coolant coming out the exhaust too. If it's flooding the cylinder enough that it's misfiring, it won't smoke, it'll just pass coolant out the exhaust valve. Since there is likely a little bit of overlap between the intake/exhaust valves, you're pumping coolant vapor back up into the intake manifold.

 

Or, like others have said, a cracked head. It's gotta be one of those two. 

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The only L (4 cylinder) series intake that is not coolant warmed/cooled is the '75-'77 L20B. This uses the U67 head which is also not drilled out for this.

 

All other L4 heads and intakes including the SU intake flow coolant from head through the intake runners and returns it to the thermostat by pass line.

 

 

So, if your U67 head was not drilled out and there is no coolant line to the intake then it can't be leaking there and tightening the manifold bolts will do nothing. Go look at the front of the thermostat housing. There will be a fitting with a short hose on it going to a metal line that goes down over the front of the timing chain cover to the lower rad hose inlet to the water pump. If that metal line has a Y in it that also goes over to the intake and is connected to it then you may have a problem. 

 

 

I have no idea where you are because your profile is not filled out. For all I know you are in Alaska and you froze up and cracked the head and that's your leak. That or the head gasket is leaking.

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The only L (4 cylinder) series intake that is not coolant warmed/cooled is the '75-'77 L20B. This uses the U67 head which is also not drilled out for this.

 

All other L4 heads and intakes including the SU intake flow coolant from head through the intake runners and returns it to the thermostat by pass line.

 

 

So, if your U67 head was not drilled out and there is no coolant line to the intake then it can't be leaking there and tightening the manifold bolts will do nothing. Go look at the front of the thermostat housing. There will be a fitting with a short hose on it going to a metal line that goes down over the front of the timing chain cover to the lower rad hose inlet to the water pump. If that metal line has a Y in it that also goes over to the intake and is connected to it then you may have a problem.

 

 

I have no idea where you are because your profile is not filled out. For all I know you are in Alaska and you froze up and cracked the head and that's your leak. That or the head gasket is leaking.

Hey there Mike. Interesting notes about the l20b and u67. I'll have to snap a few pictures of my setup. Needless to say, I'm still learning about it...consequence of buying from an uninformed seller. I just checked, and i do not have the thermostat outlet you describe, or the metal line, or the y at the coolant inlet (just for the heater). Looks like the thermostat may have had a port blocked off. This engine, to me, was assembled with some old school techniques...but that's just an impression.

 

I'm in colorado. Not a tough winter at all this year...no snow and not really cold. Car is stored in an indie garage and while that doesn't guarantee guard against freezing, it does make it less likely. That said, there were no leaks prior to the first incident that prompted this post, so i don't know what the catalyst was.

 

I'll continue with tear down and post an update soon. I'm thinking i may be in the market for a new u67 head. Tired of the constant battle with this thing not running.

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Forgot to include a few details, which could be helpful for others in the future. While exploring the issue of draining antifreeze, i pulled the spark plugs. Engine is running rich, but that's another issue. But what is notable is that after a few days of the plugs being out, cylinder #2 filled with antifreeze too the point it was over flowing. More clues as to the issue.

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Catastrophic headgasket failure or cracked/severely warped head. Don’t worry about drilling the water passages for the intake, not worth the time and effort. I’ve been running nearly your identical setup near tahoe California for well over a decade with zero issues.

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Thanks for the reply. I'm hopeful the issue ends with the head as i really don't want issues with the block. I'll be pulling the head this weekend and get it over to have a pressure test done.

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It could be the block but they’re pretty damn stout unless overbored.

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The water cooling/heating is for extremes of weather that's all. The intake gets baked by the hot exhaust just inches away. In colder weather the intake is warmed. All this keeps the intake air somewhat more confined in a range of temperature. Performance is less disrupted.

 

Dolomite.... you are used to how it runs and accept it as running without issues.    

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No Mike, it runs better than pretty much any dual carbed vehicle I’ve seen.

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So the weather warmed up a bit and I found some free time to invest in tearing down the l20b.  I pulled the head and found a surprise.  My surprise is that my pistons had been decked - sorta - by the mechanic that rebuilt my l20b.  Suprise!  I never asked him to do this and he didn't clear it with me.  I was worried about being too high on compression, but didn't know this was his solution.  Oh well I guess.  But, photos also confirm cylinder #2 is the main culprit in the missing antifreeze.  I don't see any cracks in the cylinder wall of #2...so that's good.  I haven't pulled the gasket off yet as I wanted to get the forum's insights/questions first.  I plan on bringing the head to a machine shop next week.  I believe the black on the head is from the new rings still seating, but could also be running rich as well.  Anyways, on to the photos:

 

th_IMG_5130_zpsjmhe6op4.jpg

 

th_IMG_5152_zpsknm50wwc.jpg

 

th_IMG_5141_zpsayyqhbzv.jpg

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Also, what is interesting, is that while mixing of oil/anti-freeze is seen in the head, the oil on the dip stick is clear and I didn't see mixing in the radiator when I filled it.  I will recheck the dipstick again when I pull the gasket off to be sure.  I'm thinking of changing the antifreeze out anyways, and will change the oil upon rebuild.

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I didn't read this whole thread again, but if it was just rebuilt, maybe it just needs a new head gasket.

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Take it back to said mechanic.

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