engine and drivetrain Failure of a guibo, or other diagnosis? (fixed!)

[KFunk]

I'm just wondering if a failing guibo can make an engine seem to run really rough/surge.

Yesterday was my first day with the new 215-50-13 R-tires on solid pavement, and with some horsepower to make them go (DCOEs, need jetted right yet). First couple runs were great, but had lots of wheel spin off the line, and real trouble getting into 2nd gear. By the third run, things were starting to feel 'lumpy' in the drivetrain. Something not quite right. On 4th run, things went to crap, and it felt like it was on 3 cylinders, and engine seemed to cut-out like I was hitting a rev-limiter whenever I hit the gas. It'd go solid once I got it moving quick, but then itd stumble again getting up to speed.

I checked the engine over for loose wires and obvious things, seems to rev smooth while parked. Should be no fuel issues since I'm running carter rotary pump. 5th (last) run I just let it stumble the whole way, and wiped out some cones.

Afterward, I pulled the valve cover and all rockers appeared OK (I had been hitting 7K+ way too much anyway, on original engine with 250K+ miles). Points look OK. I suspect the carbs since I just put them on last weekend, after they've been sitting in someone's garage for 15-20+ years. They were soaked in gasoline, bolted on, and lightly tuned. Pulled the top off carbs, and no obvious problems with floats or anything. Venturis seem to be in there right. I don't know at all what I'm doing with the DCOEs, and have tried to be coached over the phone from Stacey on the FAQ.

Went into limp mode to get hit home, ~100 miles. Still surged bad when accelerating. Some hollow metal rattling sounds. Made it 20+ miles, when a bolt ripped out of the guibo, rubber and all. Still kept on limping, felt extremely rough when I got over 3.5K, and another bolt ripped out instantly. I made it within 40 miles of home, and lost a couple more bolts, before deciding to call the AAA express.

So, could the failing guibo could've caused the first symptoms, or would the rough running engine cause the guibo to fall apart?

I've got an autocross I need to run next weekend, and not much time to work on the car at all. I've ordered a guibo, and thinking I oughta order rebuild kits for the DCOEs as well. I'm not sure if they're really the problem though, since they look clean inside.

I'll try to do a compression test real quick as well. Not a big deal if things have blown apart, as I've been wanting to rebuild it anyways.

But yes, it was really fast, and I still beat many of the much quicker cars even with my first run being my best. I could've picked up a couple seconds, even with my uneducated driving ability. Can't wait to get things in better shape and go again.

Thanks for any ideas! I haven't been on here much lately, too busy with work and doin stuff to the car.

[POP3Y3]

could it be that it just feels like there is a problem besides the guibo? i know when mine was going out it felt (actually it was shredded to bits) as if there was an engine problem (missing) when accelerating. replaced and all was good.[/b]

[Guest Anonymous]

check engine mounts and center bearing on drive shaft as well

[ray_]

I understand you can tear up the tail end of the gearbox driving with a wasted guibo. Be careful out there.

Cheers,

Ray

[KFunk]

could it be that it just feels like there is a problem besides the guibo? i know when mine was going out it felt (actually it was shredded to bits) as if there was an engine problem (missing) when accelerating. replaced and all was good.[/b]

Thats what I'm asking, whether it just felt rough due to the guibo.

But, didn't I actually drive your car at that time? It was just kind of a vibration then.

This was way, way worse. It doesn't seem to me like the guibo could cause that, but a friend had similar symptoms in his 635csi when rubber came blowing out of the guibo right on the autocross course. I can't get in touch with him about the final diagnosis/description about it, can't find his contact info.

The engine mounts look OK, but the engine does shake a bit at idle due to the carbs being too roughly tuned/jetted. Center bearing was changed a year and a half ago, but I changed the guibo due to cracks/vibration only ~6 months ago. At that time, I made sure to align the driveshaft properly, but the bolts still got loose too often.

Thanks for the warning Ray, hope I didn't mess it up already.

[POP3Y3]

a couple weeks or so after you drove mine i had to order a guibo. that took a week. so by the time i got it replaced it was 4 weeks of daily driving and it got pretty bad. so bad that my mechanic had to custom weld the end of my drive shaft because it beat the hell out of the drive shaft flange. so where as you may have a different problem i just wanted to let you know how bad mine was. one way i figured that the vibration was solely from that was if i was driving at any speed i put it in neutral to stop drive shaft movement and the vibe stopped.

[KFunk]

ahh, well we could do some fun welding this weekend. If the car isn't driveable by Sunday, I'll probably se eif I can borrow someone else's FSP legal street car. I just gotta basically show up and then I'll have the FSP points championship locked up in Ohio Valley Region. It doesn't really mean much since there's only a couple guys that are that competitive for it, but it'll be fun to tell people and sound cool.

I just mainly want to see what the car is really capable of, once I get it to hold together. I also want to beat the Datsun 510 that shows up on rare occasions.

[POP3Y3]

i want to go to one of your races. where are they usually held? anywhere around cincinnati?

[TobyB]

Sounds like a vacuum leak at the base of the carb(s)-

they do seem to enjoy leaking there.

But fix the guibo, then budget some time for carb troubleshooting-

take the floats off and shake 'em, check the cold-start circuit to make sure

it's not leaking, etc etc.

The DCOE's are by far the most complicated weber carb since you can

tune everything, but they're also about the easiest to work on, tune, and

rejet once you get comfy with 'em.

imho,

t

[KFunk]

i want to go to one of your races. where are they usually held? anywhere around cincinnati?

Sunday at Cooper Stadium in Columbus (where Columbus Clippers, the AAA team plays), then the next one will be Oct. 20th. You're always welcome to run or just ride along, and I'll throw you in to a lot of friends' cars just for fun. The turbo E30 is always impressive to ride in.

Closer to you, there is the Cincy Region, and it looks like their next solo event is Sept. 9th at River Downs. That's too far for me, plus I'll be running the miata that sunday in Columbus.

http://www.cincyscca.com/

[POP3Y3]

sounds cool. i'd love to go to one sometime. maybe Columbus. it's only a bit more than 2 hours away.

btw, do you know any 02'ers in maui? i'm going there in a couple weeks

[KFunk]

sounds cool. i'd love to go to one sometime. maybe Columbus. it's only a bit more than 2 hours away.

btw, do you know any 02'ers in maui? i'm going there in a couple weeks

If you're interested in running Sunday, then pre-register at www.dlbracing.com by Thursday. Otherwise, ya gotta show up at like 7am atleast to get one of the limited walk-in spots.

There's not any 02ers I know of on Maui, possibly an M2 around but I don't know the guy. There's a couple M3 guys and such, check on bimmerforums.com in the Hawaii section, several Maui guys post there. There was a squaretail abandoned on Haleakala last time I was there, and it wouldn't surprise me if its still there.

Maui has the best roads of all the hawaiian islands.

Definitely drive up Haleakala. The roads around the northwest from Kahalui to Lahaina are fun as well. But don't risk a valuable rental car around the roads on the northwest side. It is very narrow cliffsides with loose rocks and very little room for two cars to pass.

The road to Hana is legendary of course, but I didn't have time to drive it when I was there. But most of all, enjoy yourself. Just chill on the beach and do nothing, if thats what you'd rather do.

[POP3Y3]

But most of all, enjoy yourself. Just chill on the beach and do nothing,

... and play a round of golf! i am trying to get in contact with a couple musicians there and perhaps sit in or find an open jam.

[KFunk]

But most of all, enjoy yourself. Just chill on the beach and do nothing,

... and play a round of golf! i am trying to get in contact with a couple musicians there and perhaps sit in or find an open jam.

I lost the mp3, but see if you can find 'John Cruz - Island Style' somewhere online and download it. That'll set you in the right direction.

[KFunk]

OK, guibo is on the way, should be delivered Friday. Getting new OEM bolts/locknuts from Max.

The 02 is at parents' house 20 minutes away, I'm gonna head up and see if I can figure out anything else tomorrow night. I'll jack it up and check out the flanges (I need to swap the wheels/tires from it anyways, to use on my miata).

But while I'm there, I better diagnose that the carbs are working OK. The problem is that when it sits at idle, and u push the throttle, it revs just fine. I guess I'll blast some carb cleaner around to look for vacuum leaks. If its just at the base of the carb, will some silicone gooped on be a good temp fix?

When I looked under the front carb yesterday, I did notice the pump rod had a tendency to stick in the 'up' position when i pulled on it, while it instantly retracted in the back carb. Any ideas if that could be a prob? I had wiggled it till it seemed to retract fine, but that didn't help.

Oh, and I was waiting to brag about it later, but here's the full kit I bought:

carbs, warneford manifold, filters, linkage, velocity stacks, original box and instructions, all for $500. Apparently it was a full kit sold by the defunct company 'Karzundpartz' from Greenesboro, NC. The guy had used them for a year on his 75, then took them off and sold the car. He put the carbs back in the box and kept them for many years, until he spotted me on the street in Athens, OH getting into my 02.

I quickly jumped, and here they are installed:

The only problem is they were jetted for a re-ground cam, and I have a stock cam. But they run, and they're a heck of a lot of fun. It just goes. Don't think I'll ever want to go back to downdraft.

Thanks much to Charlie for the deal. I've told him about the site, and he's been looking around on here and may start selling off other parts he has stashed away. He's also still got his wife's 75 '02 that he's getting in running condition to sell. He also hooked up my boss with a deal on a nearly brand new flywheel/clutch/pressure plate for his son's 73 '02.

A great guy, and hard to believe there was another 02er from way back right in my hometown.