Repower MCI 7

edvanland · June 11, 2016, 05:25:34 PM

Any ideas on a repower MCI 7 ? has a 8v92 with Allison 740 trans and I can not keep the thing cool. Has new radiators, extra 24x40x4inch radiator, new fan seals, smaller pulley to make fan go faster, separate trans cooler with own cooling system which then goes back to the original cooler, I am at my wits end. Any help would be appreciated. I know is cost money any idea how much and where to get it done? I am in Cornville AZ 100 miles north of Phoenix.
Thanks

chessie4905 · June 11, 2016, 06:05:50 PM

Be cheaper and easier to reduce injector and possibly turbo size. What size are the current injectors. Get a heat gun and verify your gage is accurate. Also misters will help if only overheating on long hills. Do you have 92sized radiators?

edvanland · June 11, 2016, 06:15:52 PM

Don't know about 92 sized radiators, they are 5 row with dimples and are as big as can be put in a MCI 7. I have extra radiator an misting system. I think the ejectors are 500 I will have to check that out. I also have to check out the radiator.
Thanks

gumpy · June 11, 2016, 06:32:42 PM

Those may be the standard radiator, and would not be sufficient for an 8V92. Pretty sure that bus didn't come with that engine.
You can put bigger one's in, but you'll probably need to modify the firewall. I had to do this on my MC9. Photos in my bus site.

Make sure you have all seals around the radiators tight, and that your blower door seal is tight. The door seal alone can defeat the whole cooling system. Air has to flow through the radiator, not around it. Those two items are the most critical.

Also, as indicated in a previous comment, make sure your gauge is accurate. Install a gauge in the rear, or get some thermistors or other means to record actual temperature.

TomC · June 11, 2016, 07:01:33 PM

500 is not an injector size. On a 92 series it would be a 9A90 or 9G85 or similar. Want to reduce your over heating? Don't use the power. Let the bus slow down and down shift when going over a hill. Or if you can't control yourself with the gas pedal, reduce the injectors to 9G75. That will put you at about what a 6V-92 would put out. Good Luck, TomC

Scott & Heather · June 11, 2016, 08:14:27 PM

It's not the 8v92's fault, even tho they are notoriously hard to cool. My 8v92 in my 102C3 has 8 tube rads. Your rads can't even hope to keep up. I've never overheated my 8v92 even when the temp was triple digits and I was climbing. Granted I have two new radiators, new blower fans new mitre box and very tightly rebuilt and sealed blower box. But you're never ever going to keep an 8v92 cool with 5 tube rads. No way.

Sent from my iPhone using Tapatalk

chessie4905 · June 12, 2016, 07:04:27 AM

If you go to the tune up section in the 8V-92 service manuals, they list the specs for the various states of tune with injector size,injector setting, delay setting,turbo size and model, boost pressure for different years of mfg. I have a 92 brochure that lists 400 and 450 hp that uses same 9g90 injectors and different turbo numbers. Injectors are most likely set with different pin also. Unfortunately I haven't seen heat rejection numbers except one brochure I have that lists it for a 400hp 8V-71.

luvrbus · June 12, 2016, 07:21:43 AM

The 9A90 was used by MCI they can go from 335 to 435 hp in a 8v92 I came across a lot of MCI 9 that were 8v92TA that only were 350 hp but were 1250 ft lbs of torque MCI also had 8v92 N/A engines they weren't much

edvanland · June 12, 2016, 08:49:09 AM

Thanks for all the suggestions. AS I have already done the radiators, extra radiators, trans cooler, new seals on blowers and door, misters and drive like I have eggs under my foot where to next?

luvrbus · June 12, 2016, 09:03:10 AM

Since Geoff rebuilt your engine Ed he should know what the injectors are and hp rating is could be it's 475 hp.The MCI 7 combo with the 8V92 and the 1 side radiator don't seem to have the cooling problem,then it could be your engine has the large M injectors and it's just to much for the cooling

muldoonman · June 12, 2016, 09:44:56 AM

You know down here in Texas in summer and pulling a ford F150 supercrew around I have to watch it as it will climb to around 200 when you're climbing hills and running a little faster than normal.Guess you have to watch it on all of them.

gumpy · June 12, 2016, 02:14:49 PM

Just a thought. Is it possible your water pump is not pumping properly, or maybe there's a blockage in the thermostats or something? You could try removing the t-stats and see if it improves any.

chessie4905 · June 12, 2016, 02:16:05 PM

Pull a valve cover and check the tag on the injector.

Emcemv · June 12, 2016, 03:08:46 PM

We have the MC7 combo with the side radiator. We are running 450HP 8V92T. I have not been out west in triple digits to test it but so far so good for us. I am installing a new digital temp gauge on each bank because you guys have all scared me to death about overheating it. We are newbies and learned on this forum how to drive it to keep it cool. I don't know how many tubes our radiator is, guess I'm going to have to check that out.

Scott & Heather · June 13, 2016, 04:09:51 AM

Which digital gauges are you using?

Sent from my iPhone using Tapatalk