rebuilt engine experiencing blow by
 

I need some ideas and suggestions on what might have caused oil blow by.
okay I recently had my Whipple Charged 502 gen 6 engine rebuilt. the block was punched out to .30 over I also had a different cam shaft installed.
which brings up a major problem. tuning the ECU. The engine was rebulit by a builder who has a very good Reputation, but could not remap the ECU. The motor was installed last week and ran it for about 2 hrs varying the rpm as the bulider suggested boat ran great. egt gage never went passed 1250. The Probe is reading the temp of the #4 cyl. pulled the #1and 2 spark plugs they looked gray in color. I called the guy here in Arizona who can remap the ECU brought the boat over to him he did his thing. I was not with him when he remapped the ECU. He wrote on the bill I quote " engine appears to be consuming oil. oil comsumption is causing detonation at running temperature. Port side of engine is running richer than starboard. These conditions may be caused from being a new engine assm. and should be watched to see if conditions become worse after running time is increased"
Yesterday, in lake Havasu left the launch ramp all the gauges looked normal. brought the boat up on plane and was cruising around 3500 rpm egt around 1150 . About a mile or so the oil pressure dropped to 20 PSI I shut off the engine. In the mean time my kids started to yell Dad smoke is coming from the engine hatch. I opened to find oil all over the place. man what a mess.
The breather on the port side valve cover blew off. After cleaning up most off the mess I checked the oil level it was down a QT.
put a QT back in and started the motor oil pressure back to normal gave it some gas and the breather blew off again. I opened the oil filler and noticed that smoke and air was coming up from the crank case. Today I pulled all the spark plugs all looked about the same. All black and the threads appeared to have oil on them. One last note last week when I checked the number 1 and 2 plugs, I checked the oil it was so clean I found it hard to see on the dip stick. before I left for lake havasu I checked the oil after the remapping. It was black and had the smell of fuel. I changed the oil and filter before I left. As you can see I'm in for alot of finger pointing. I called the guy who built the motor his initial comment was a hole punched in the piston. If the motor ran lean and put a hole in the piston what would the spark plug look like ? Thanks in advance for your response.:confused: :mad:

If you holed a piston you would be able to see aluminum on the spark plug when viewed with an illuminated plug viewer. Check your compression!!! If one cyl is the culprit it will be down compared to the other cyls. Other causes could be improperly phased rings or excessive ring end gap. If the rings are phased improperly the flame could act like a torch and damage the rings and pistons. I would check compression and see what you have. Good luck.

I agree --you have holes in your pistons. The gray on the plugs is aluminum from your pistons. Also I don't think #4 is the hot cylinder. I have my EGT in #6. When you run VERY lean you can have a low EGT.

heads off
 

sounds to me like its time for the heads to come off. You can point a more powerfull finger with the facts. You might have a blown head gasket.

Could it be that the new fuel mix is so rich that the gas is washing down the cylinders? That would explain the black oil and the gas smell. It could also explain the excessive blowby that is blowing out the valve cover breathers. Gas washed cylinders will not seal. The engine is also still fairly new and may not have had time to break-in the rings. I would pull the plugs and just stick my finger over the plug hole while someone cranks the motor. (Don't forget to disable the ignition so a spark from a wire does not ignite any raw gas) If you have holed pistons you will be able to tell very easily as there will be a noticeable difference in the suction and pressure from the plug holes. Good luck. I hope your pistons are OK. If they are, your issue is with the fuel mapping guy. Otherwise you have a mess. Sorry.

Most of the damage may already have been done before it was remaped.

jdelo,

I am sorry to hear about your engine. I had my engine rebuilt by two different builders in phoenix and I was dissapointed with both shops. The best boat shop I know of will only put in new motors because of the problems with the engine builders in phoenix. My new motor is running great but it took 3 builds to get it right. If you find any one that does good work in phoenix PLEASE let me know.

I would do a compression check, drain the oil and cut the filter and you should know the story.

Let us know how it turns out

jdelo,

Also sorry to hear of your problems, however, before going much further than a compression check I would ask a few more quesitons... The previous posts are right on the money and
the fuel wash-down seems to be exactly on the mark with
the color and odor of the oil... Sorry I can't be of help with
the injected motors, but after I experienced the same fun
I had problems getting the rings to finally seat given the
lower operating tempratures of a raw cooling system...
Ended up having to force heat the motors before the issue
was finally cleared... Best of luck...

Karl

Thanks for the feedback all of you have given me. I new I could count on fellow members. :) :) :) :) :)

I took he boat over to the engine builder today. He's very interested as to why the motor failed. He said he would make it right we will see.
He asked me a few more questions about the idle and if the engine was miss firing. Motor idle fine and no miss fire that I can tell. He is leaning away from a hole in the pistons. We talked about the washdown effect. thats a big possiblity.

back to my first trip to the lake. The motor ran fine maybe a little bit on the lean side but no blow by. Question is it possible for the rings to seat and than unseat do to the gas washdown effect ?
Thunder 1 how did you force heat the motor. the builder told me that if the cyl where washed down the motor has to be rebuilt.

Keep in mind I am not trying to insult anyones intelligence here. I only say this because I saw it on another boat. Are there any extra hoses going into the valve covers that are on the pressure side of the blower? It seems to me if the breather blows off that easy there is alot of pressure in the crankcase. A hole in the piston or pistons would surely cause a misfire.
I did see one time a misrouted breather hose that was pressurizing the crankcase and would blow oil out the breather almost instantly. Just an idea.

sorry to hear it. ouch. i think you blew a hole in a piston also. the gasoline doesn't have the lubrication qualities of oil and wouldn't stop your rings from seating in my opinion. even if they didn't seat yet i don't think a breather would blow off and enough crancase pressure to blow oil out, only a blown pison would. you may consider yourself lucky though because you didn't have a crankcase fire.

jdelo,

I am quite sure you are right about the piston scenario since it would idle like garbage and the blow-by would be synchronus with the bad hole... To get the temprature up I fed
H2O to the headers directly from another source and from still another souce fed the engine with the sea pump disabled, the
feed being on the engine side of the sea pump... By using a
water hose you can regulate the quantity and temprature by
actual flow... Only thing is watching the temprature and holding
at about 220 degrees for .5 hour... Some folks suggested more
temprature but the only thing holding me back was fear and
common sense... Hope this helps...

Karl:) :)

Heres an update as of last night. I talked with the engine builder and here's what he said. did a leakdown and compression check. all cyl checked out fine except for the #4 cyl. zero compression. I said to him hole in the piston? he said looking at the spark plug I don't think so. He's pulling the engine today. I will know the exact cause of failure thursday. It's ironic the EGT probe is installed in the #4 cyl 1250 is the highest temp I saw. in fact when the failure happened the pyro was reading 1150. stay tuned

The results are in.
Holes punched in the pistons. all eight # 4 and # 2 are the worst.

The guy who built the motor even though he didn't do the ECU remapping is going to help ease the pain.
It's now time to go see the guy with the computer and see what he has to say.

Sounds like terrible luck you had, I replied to your other post about the fuel injection, and it sounds like you need a system that would constantly adjust to the demands of the motor. I have been researching this to build one for my boat. Also the Holley Commander 950 is a good system. I don't think preprogrammed PROMs can accomodate blower motors in boats well enough to not have this come up again. I know a guy who blew his blower motor up three last year. The bright side, just learn from the mistake and don't repeat it. Good luck.

jdelo,
did you look at all eight pistons? they were all melted or cracked? did you happen to notice if any exhaust valves were bent. i've melted pistons all the way down to the rings before too but it was only three cylinders out of eight. all eight with holes is pretty rare. what i'm getting at is if your springs were too light it may have caused some valve float at high rpm's. just another possibility to look at. sorry to hear about your engine. that sucks. Fran

excaleagle42

Let's me explain it to you this way.

2,4, 1,5, with holes burnt through # 4 took the worst hit. the rest were about to go. JE pistons All in the same location the valve relief.
What really sucks is the GM ECU. If you make any modifications to your engine from what I understand, thier are only three people in the USA who can go in and make changes.


jdelo

“What really sucks is the GM ECU. If you make any modifications to your engine from what I understand, thier are only three people in the USA who can go in and make changes.”

jdelo’
can you explain more in detail what you mean? did you mean, three independent people in the USA who can legally go in and make changes, or three people who have the knowledge or the tools? don’t get me wrong, i don’t know any thing about it. it’s just, that doesn’t seem to make sense to me, with 10s of millions of GM ECUs in the US why would there only be three? they would need more than that at just one GM plant. where did you here that?

Dean,

Here's how I understand it. GM PowerTrain designed the MEFI 3 for Mercury Marine. Merc didn't want anyone to have access to the software because of Warranty issues. Only a select few had access to it due to thier inluence with mercury Marine. One guy on the East coast one Guy in the Mid west and One guy here in arizona. Go and ask your local merc service guy. I bet he will tell you the same thing or we will not know what your talking about.

what sucks is that every member on this board who has the GM MEFI-3 fuel management system, is at the merci of a select few. Guys who what to make modifications or just want to tinker are Sh@t out of luck.

Check out this thead.

www.diy-efi.org/gmecm/html_archives/archive_num_12c/msg00384.html