After working through porting, rebuilding and installing my Cosmo 13BRE into my 95 FD, it now appears to be burning coolant. First big, white cloud of smoke appeared yesterday at startup.



I've been upping the boost slowly and tuning as I go (PFC w/Datalogit and wideband o2). I'm now up to about 8kg/cm2. I noticed last week that the car was running a bit rougher and I believed it to be nothing more than needing new plugs as the plugs (non plats) in there were installed when the new motor was dropped in. I'm at about 3500 miles on the new motor. Break-in was 1,500 miles and I went to extensive lengths to keep temps in check. They run between 82 and 87 celcius with a front mount. If the sun doesn't come out, it'll sit at 80 forever.



Now the rough running has been coinciding with boost increase but my vacuum readings at idle have not changed. I monitor everything and knock hasn't been present (most of my readings are single digits with 39 being about the highest ever).



Yesterday I did a short run in third to log some data. I get home and the engine is running rough. Look at the logs. Fuel is fine. No knock. I shut it off. Start it again, big plumes of white smoke and the tell-tale sweet (ironic) smell of coolant. I shut it off in disgust and go in for the night.



Here's where it gets wierd. I get the same thing in the morning. Hard to start, coolant smoke coming out the back. It clears up a bit and I drive down the road (did the same thing leaving from work the day before). Eventually it clears up. Idle is fine. Buttery almost. Vacuum is right where it should be. If I boost however, especially above .5kg/cm2, it'll run rough and blow white plumes out the back after shutting the car off and turning it back on.



I have no doubt it's a coolant leak which is allowing coolant to get into the combustion chamber. What I'm wondering is why does it get better as the car gets warmed up (metal expands, provides better "sealing"?) or is the pressure of combustion keeping the coolant in place? I boost and it forces the combustion pressure in and some coolant out? Just seems like it would leak ALL the time and steadily get worse as the car warmed up.



We'll run some tests on Tuesday and probably end up pulling the motor again. It's really getting old. I honestly don't think the motor was torqued correctly and/or the tension bolts and threads were not cleaned which causes a bit of separation between housings/plates under boost. An OEM motor should be able to withstand 2.0kg without dowel pinning...you'd think 8kg would be nothing!

Who rebuilt the motor? What's the history on it?



It does sound like that either one of the rotor housings is warped (tell tale sign is the lower dowel pin will be stuck in the housing) or one of the inner water jacket o-rings is pinched (likely, seeing how the engine is new and could've happened during assembly).



B

True true...I did think about the pinched ring. It's a used Cosmo 13B RE imported from Japan. Took it apart and it looked virtually brand new inside. We used new everything inside with upgraded stationary gears, oil pressure regulator, etc...anything that was better in the FD's design we used on the Cosmo. The shop (remaining nameless for the time being) said everything was checked including the plates for warpage, etc...I do know that if you don't clean out the threads and bolt holes, it'll give you improper torque readings as well.

that sucks....atleast you know how to fix it https://www.nopistons.com/forums/pub...IR#>/smile.png

I pinched a O-ring on a engine this weekend, it sucks

I tell you though, it's really wierd. I'll get rough running immediately after boosting. No smoke. I shut the car off. Start it up again after letting it sit, smoke. Run the engine for a bit by driving it around and it clears up. I can drive it all day at very small boost levels or no boost at all and it runs as normal! Normal vacuum, etc...



I actually didn't put the engine together, a local shop did. I'll be a bit better educated on what I'm going to do when I pull the engine and take it apart. Who knows, I may be calling Judge to build me an engine :-)

Michel

don't call him yet. he is on vacay in puerto rico. i told him to bring me back something cool https://www.nopistons.com/forums/pub...IR#>/smile.png



my engine is great.... its the only thing i don't have a problem with. its everything else that i break.... now having ignition problems woohoo

I was in the same boat as you were, after putting it back in just to have the same problem. I ended up having a small crack in the front intake port that was let the coolant in. I wasn't the best person to be around that week.

holes where there are not supposed to be holes is a very bad situation!

live and learn, sure I will be doing it again

so is it fixed now todd ?

I am breakin it is right now, I have 600klm done so far only 400 more and she is going to get tuned. I have given it a little boost, I am very happy the t-88 seems to be spooling earlier than I thought. I need to take some pictures and send them to ya.

I'm not sure if you took it apart yet, but if you didn't you could re-torque the tension bolts by removing the transmission and see what happens before you pull and tear down the whole motor again.

Either good luck with that and don't let it bum you out man.

Not out yet but it will be tomorrow. We did a few tests and finally pulled the plugs. Turned her over and she sprayed coolant out the rear housing. So...pulling her apart. I think it'd be almost impossible to just throw out coolant if the engine wasnt' torqued correctly. I'd be loosing oil (although it HAS been using more oil than it should). I'll take pics and let everyone know what the diagnosis is...Not sure what I'm going to do if it's a hairline crack in one of the intake ports. If it's really small, I may have it welded and just go with it.



On another note, anyone know if the REW plates are the only ones that are nitride hardened on the face? I just heard that it was the first to receive this new treatment. I'm wondering if the RE plates on the 2 rotor cosmo and 3 rotor cosmo have the same hardened surface. I'm asking because I have heard that due to this treatment, you cannot lap a third gen plate.

I'm sorry to hear about the new problem. Was looking forward to seeing how this sucker turned out with the big streetport.

At work (in the hydraulic field) we build bankable valves in witch they receive some o-rings in between the sections. Every once and a while a valve will come back because it started to leak after X amount of hrs of use. Almost 100% of the time it's due to a pinched o-ring durring assembly. The o-ring will seal for a while untill it gives out due to pressure spikes or just regular use. Maybe this is what happened to your coolant seal? Hope so, it's a lot cheeper to fix then a hairline crack in one of the ports. :(

I hope you're right! If so, I won't have to foot the bill :-) The engine feels pretty strong. I've gone through and tuned on the street up to about .9kg/cm2 with a safe/rich high 10's for air fuel ratio until I can slap her on the dyno and really start tuning with fuel and timing. At .75-8kg I can outrun a BPU Supra and/or a supercharged S2000 quite easily, LOL.

Michel

I'm pretty sure the cosmo motors are nitrided as well. The plates can be lapped, but they need to be re-nitrided again afterwards. https://www.nopistons.com/forums/pub...IR#>/smile.png

Really...didn't know you could re-nitride them! Wonder who does that in the states. Anyway, the verdict is in, I got a bit overzealous in the bottom of the primary runners creating a bit of a thin spot. You can feel it, but can't really see a hole per se. Looking at the two primary runners internally, there's a disk-shaped coloration in the bottom of both ports, almost like there's a plug or something left from the casting process. for some reason, the front rotor primary was a bit porous in that area. It's pretty small.



Anyway, the engine is apart and everything came out fine. No bad seals, housings, etc..One issue that I did note was a small 'burn" spot on the rear E-shaft journal. It's on the very back edge and it wore a thin (few thousanths) ring around the rotor bearing exposing the brass. We're replacing the bearing but for the life of me, I can't figure out what it would hit to cause that. If you run your fingers around the edge of the journal, it's fairly sharp. Well where it melds back into the length of the shaft, it gets rough for about 1.5 inches and is discolored due to heat. We'ere checking to see if the shaft is still good (looks like it should be) but I'd like to figure out what caused that. It was fairly difficult to get the rear rotor off the shaft. No spun bearing however and the bearing face looked brand new.



So...lesson learned. I'll let someone else do the port job next time. Although I learned, if you can't afford the downtime/rebuild while you're "learning", let the experts do it.



I'm now in the search for a new Cosmo intermediate plate. Vosko, is Judge back from vacation yet?

did they put oil on the threads of the torsen bolts when they torked them? If not that will definitly cause improper tork.. You might be able to drop the mission and pull the flywheel and retork them one at a time using the tork sequence.. Ie. pull #1 clean the threads, put oil on the threads and tork it, then do #2 and so on..

Sorry to hear about your misfortune Michel

Makes me feel good to know my ports are still holding up like Mt. Rushmore.



Goodluck next time around. Post pics next time. https://www.nopistons.com/forums/pub...IR#>/smile.png

that sucks and the judge is not back from vacay yet

After searching high and low for a Cosmo intermediate plate, I gave up and called Pineapple. Although they did not have one, I asked about their experience with epoxy and based on the info they've given me, I have decided to go that route. It's not over-the-shelf stuff I'll be using but about $50+ for both parts a/b in pint size. I'll have a bit left over :-)



Anyway, they use this stuff in their bridge port and it'll last for years without problem. My "hole" isn't much of a hole (you can barely feel it with your finger) which will present a bit of a challenge. It won't take much to seal the sucker up though and I won't have to go through the whole porting process again. My main priority is to get the car up and running and I think this stuff will do it. I'll report back after I've done the "epoxy mod" :-)

yup you need to do that on giant ports.....

Why not weld?



It's been done before. Just takes a bit of patience (not too much at a time)



Use a piece of copper behind the hole and mig weld through the port- it'll be a more permanent fix than the epoxy. Grind back and smooth as per porting.



The epoxy will probably work fine, and as vosko says, some ports need epoxy in the aluminum housings to block off the coolant channels (and also in the iron plates on PP's I think).



Just my two cents... https://www.nopistons.com/forums/pub...IR#>/smile.png

Just use a FD intermediate housing and port it down to match the intake runners, you may lose a little port volume, but no much and it won't leak. I don't think I would trust epoxy on somthing that will be daily driven. If you do use the epoxy then fill the water jacket around the port, but don't actually put anyting in the port. I'm assuming your already going to do it that way, but just incase I thought I'd mention it. No since in sucking a chunk of **** in to your engine and taking somthing out that's important like a apex seal or ex wheel on the turbo..

I'll take a pic to show the area I'm fixing. I can't get at it from behind which is why we can't weld it unfortunately. Thought about the REW plate but again, I'd have to really hog the runners out as the LIM has already been ported to "cosmo" specs otherwise I'm looking at port reversion caused by the lip. Plus it'll take so damn long to get an REW plate, port it and get it ready to go...with epoxy, I'll be on the road in two days or so. It's about to become a weekend car very, very soon as well :-)

Michel

just fyi every plate has been nitraded since 1978. the non nitraded motors are spotable by black painted irons



mike

and can't you lap the treated ones you just won't have as hard of a face afterwards (pre-78 wear characteristics afterwards) which might not be a big deal for you if it's a largely ported motor that isn't expecting many miles anyways.