Chrysler 90hp... old. AUSSIE BLOKE NEEDS AMERICAN KNOWLEDGE PLEASE!! :)

[Steven Bates]

Hi all, this is my first post... love the site and have found many answers to questions by just looking thru previous posts...

Herein lies my problem... Here in Australia Chrysler motors are treated like the devils work!!! having had old mercs and evinrudes in the past i found this motor to be extremely smooth and quiet i like it! go you tough chrysler!!

I got onto a boat and motor cheap, restored boat and put new impeller in WP. took it out for a run, no worries. took it out again and after approx 20 mins running heard a bit of a bang- followed by an inability to re start. got it home, set up with ears and started it again...
Engine backfired a bit on start up, then ran "roughly"... seemed to be vibrating a bit. still hit max revs when opened up though... was no sign of water in cylinders on removal of plugs, but i decided to test compression to see what it said...
cyl 1 (top)= 138psi. cyl 2 (middle)= 134psi... all good cyl 3(bottom)= uh oh- 105 psi...
now having said this tried the old "oil down plug holes" to check rings- sadly no real improvement
what im as

 

[Steven Bates]

Re: Chrysler 90hp... old. AUSSIE BLOKE NEEDS AMERICAN KNOWLEDGE PLEASE!!

I'd also love some ifo on my motor if anyone has the knowledge/means to find out? the motor is a Chrysler 90 "magnapower"... electric start & choke... mod no: 907HA ser no : 6790 thanks again.
Also when just collecting numbers i noticed a water/ oil (grey coloured) blend of slush coming back into air box/ intake... uh-oh... lol

 

[Steven Bates]

Re: Chrysler 90hp... old. AUSSIE BLOKE NEEDS AMERICAN KNOWLEDGE PLEASE!!

Apologies... still learning computers was wondering if i should try to put some of that copper head fix stuff you run in cars directly into intake pipe via pump and bucket and get hot? Is this likely a gasket issue or something more terminal?

 

[dutch420]

Re: Chrysler 90hp... old. AUSSIE BLOKE NEEDS AMERICAN KNOWLEDGE PLEASE!!

Hi welcome to iboats

Im pretty sure ur motor will run fine with a 10% difference in compression. But with this being said and u stating that u heard a bang when running the old girl, plus the fact u state.. noticed a water/ oil (grey coloured) blend of slush coming back into air box/ intake. I myself would pull the head off of the motor and have a look inside kinda sounds like u have a bad piston. And with u running it hopefully if this is the case the cyl walls are not damaged. Now i may be wrong but thats what it sounds like to me. And at the very least if u pull the head and find its just the head gasket it can be fixed and on the water in no time. and i would not waste ur money on an additive all u will end up doing is pouring ur money down the drain. Head gasket is cheap and easy to do if thats ur problem.

 

[Frank Acampora]

Re: Chrysler 90hp... old. AUSSIE BLOKE NEEDS AMERICAN KNOWLEDGE PLEASE!!

Do not use the head fixing compound. it will just pass through the engine because the cooling system is not under pressure and open, not closed.

Unfortunately, as Dutch wrote, it is time to remove the head and see the extent of the problems. I would bet on a broken ring and scuffed piston.

Additionally, if you are seeing water/oil emulsion out the airbox you may have a leaking exhaust chest cover gasket or perforated stainless plate.

So, you have a number of examinations to do and very likely with an engine this old you will also snap off at least a couple of screws on the exhaust cover.

By the name "Magna-Power" I can infer that this engine is a pre-1978 Motorola distributor ignition. Chrysler stopped using the term after changing to non distributor Prestolite ignition. The Name Magna-Power II was reserved for the very failure prone first generation distributorless ignition (which was only used on the 120, 55, and I think 105).

 

[Steven Bates]

Re: Chrysler 90hp... old. AUSSIE BLOKE NEEDS AMERICAN KNOWLEDGE PLEASE!!

Thanks a lot fellas- and not wanting to seem kiss ***- Frank, your impeller change guide from 2008 ish was the best... you made it ridiculously easy cheering to have your advice!! and of course thanks Dutch!!
I was bored this arvo so decided to rip head off anyway snapped one bolt but all good now. The bores seem to be very smooth, even in the bottom cylinder, carbon "blackness" (for want of the right word) was very similar in all three cylinder head domes- so here's hoping its not terminal damage... some further questions if I may:
I am assuming the exhaust cover is on the left side if viewed from rear- with like 20 bolts? will i be able to check damaged rings with this cover off, and replace if necessary? (access conrod pin or the like to remove piston without further engine disassembly?) On inspection the oil fuel sludge was coming from a hose that joins bottom of air intake from the bottom of the intake manifold? not really that bad- if a lil bit is ok but should i be seeing any? it seemed strange... Lastly I have read on some forums that a bad fuel mix/ leaning out was bad for pistons so i didn't want to mess around with carby end- im thinking that area must be fine if its been running so smooth for ages but I read on here (possibly another frank answer!!) to install another fuel filter between pump and carbys... Your thoughts? Thanks again- next time your in OZ i owe ya a beer.

 

[dutch420]

Re: Chrysler 90hp... old. AUSSIE BLOKE NEEDS AMERICAN KNOWLEDGE PLEASE!!

Hi steve yes the exhaust side of the motor is on the left. But u will not be able to remove the piston via con rod pin. The pins run vertical through the motor. Now if u looking at removing the pistons, u can try what i am...... I have removed the reed plate on my 85hp, now that has givin me access the the connecting rod bolts on the front side of the motor. Now when u remove the bolts be very careful . The rod cap will come off but is mechined to be but back on a certain way. Now u havw access to the needle bareings and the 2 peice race that holds em together. Dont mix bareings from the 3 diff pistons keep all parts together and take ur time reassembleing this makes the difference between make it work and make i lt last.. Good luck and if u have any questions please ask we have all been there before and are willing to share any info we can..

Cheers

 

[Steven Bates]

Re: Chrysler 90hp... old. AUSSIE BLOKE NEEDS AMERICAN KNOWLEDGE PLEASE!!

Thanks fellas- job sorted. I found it realitivly easy to do... only requiring my brides lil sexy hands to do bearings and collect the rollers from bottom of crankcase!!! took me a few hours to do, but gave me a great look at the motor. hardest bit was trying to not snap bolts everywhere- total one head bolt and 3 exhaust plate ones... all intake end came out easily carbs and reed plates clean as!!
Hopefully a quick hone and rings/ head gasket will bring it back to specs- I use a great machining shop so thats now a work in progress...
Have decided to re-power with a 82' model 125 chry for this season (just hitting summer here) and put the 90 on my old half cabin during the off season. Thanks for all the advice and help... cheers!!