Did the dyno killed my engine

[Louie85]

I just finished a DE event in thunderhill and engine ran well and decided to dyno the engine after to see how much HP my car was producing. Stock internals, 250k miles on the bottom end and about 100k miles on the P/C and rebuild heads. After the dyno on the way home my car started misfiring and then 1 loud back fire and the engine is solid wont turn over. Any Ideas.

the car is 1985 3.2 carrera SW chip and euro premuffler and dansk sportmuffler.
Dyno results
210.34 HP at the wheels.

[Mo_Gearhead]

Quote: "and the engine is solid wont turn over."
________________

Will not turn over with the starter?

Or does 'solid' mean you tried to manually turn the crankshaft by use of a bar/socket on the crank and it's locked up tight?

Edit: If the crank locked up solid while driving, the rear tires would have locked too ( I will assume it's not an automatic).

[e p slick]

It ran out of warranty at 250,000 miles. Should have dynoed at 249,000 miles while it was still relatively fresh. Chain > valves > pistons > rods > Ka-Booooom!

EPS

[911st]

What rpm did you take it on the dyno?

3.2's have a known weakness with the rod bolts.

One of the options of the SW chip is extended rpm range. With 250K miles on the rod bolts one or more may have stretched enough to pound out a bearing, loose oil pressure, stretch a rod, allow a piston to hit a head and the rod to notch a cylinder or more.

Hope I am wrong.

The best.

[crustychief]

Ouch. +1 911st

[aigel]

I once threw a rod after rebuilding a carburetor (chevy 2.8 V6) while revving the engine to check the accelerator pump. It also was a high mileage engine (180k). The special exercise I gave it obviously was different enough to trigger a rod bearing failure.

I would not be surprised if you stressed your engine on the dyno (high rpm being the most likely culprit) differently than usual and it was enough to send it over the edge.

George

[beepbeep]

Locked solid as starter won't budge it? Remove the plugs and inspect them. If one of them is oily and/or broken and engine is still "solid" when you try to crank it with plugs out, you probably dropped a valve and that cylinder is a mess.

Budget for new cylinder head, piston and cylinder.

[Mo_Gearhead]

After a good nights sleep I have concluded

...the dingo ate your baby!

[JeremyD]

Well the good news is that it was running strong - right before it died. 210 at the wheels is a solid number for a carrera. 250 on the bottom end is a number that 98% of the population would be happy with.

Now - it may be as simple as a collapsed tensioner. Or as bad as a thrown rod or dropped valve. Time to start troubleshooting - plugs first - then you may need to take off the chain covers if you can't determine anything concrete. Work from there.

[docrodg]

mmm...I love the smell of toast, which is what your engine probably is. Likely over-rev and a complete rebuild... save up money, anything could have happened on that one, but a locked up engine suggests rod failure and probably the rod jammed up in the case/cylinder. PRobably too much RPM.

[Louie85]

Thanks for all your responses. I'll post the dyno sheet later today or tomorrow. About the RPM the dyno personnel took it until the rev limiter kick in. According to the sheet its at 6800 RPM. The starter wont budged it. I'll pull the plug today.

[DarinB]

I think an over-rev at your previous track event was much more likely than a failure due to the dyno.

[911st]

Pull plugs and valve covers. Check valve clearances, try to turn motor both ways at the cooling fan.

Been there three times. A rod twice on my factory 2.4S and a tension failure once on my 930. Not fun.

I wish you the best.

[CBRacerX]

Good luck!

[Louie85]

Good news. Thanks to all your advices. Upon closer inspection and suggestions here I removed all the spark plugs and they all look fine, nice color no damages, I spun the fan to rotate the crank and it moved, move it back an forth, spun it to 1 revolution and it worked. I started to get ready for a leak down test, upon removal of the distributor cap, the rotor was up and look different, I spun the rotor and it spun, look at the back side of the distributor and it was wasted. The rotor must have been spun up and damaged all the contacts in the distributor cap. Install my old distributor cap and rotor and fired right up. Now I'm not sure why the starter didn't budge the motor. Oh well. Again thanks to all.

Warranty is still in effect........

"It ran out of warranty at 250,000 miles. Should have dynoed at 249,000 miles while it was still relatively fresh. Chain > valves > pistons > rods >"

[dtw]

Love a happy ending

Might be time for a distro rebuild though - the shaft should not float that much. How much up/down play is there?

[CBRacerX]

Great news! Pull the dist and check the drive gear and the brass gear on the crank.

[jonbot]

Reminds me of the time I heard a rattling in my engine so I had a "reputable" local Porsche mechanic take a look at it and he was convinced it was a valve guide coming loose. He quoted me for a rebuild, and I gave him a deposit. Before he started the rebuild, I took the car to the local Porsche dealer for a second opinion, they determined it was just the catalytic converter that was coming apart and rattling inside Another happy ending, got my deposit back, and dodged an engine rebuild.

[Matt Smith]

Louie that's a great thread! But just to be 100% sure, I would still tear the motor down and do a 'while you're in there' complete rebuild. You just never know what horrors they put that motor through in the dyno test. LOL! Great stuff. Keep driving that beast hard another 250 and make 100% of the people happy.

[GothingNC]

Louie,

Glad it was really a simple fix