1971 Chrysler 85 hp Loss of Power

Hello everyone,

I have a '71 Chrysler 85 hp that lost power on the last trip. Compression is #1=150, #2=150, #3=137 (psi). Have spark to all cylinders, fuel is new and correct mix, carbs seem to be working properly.
Additional problem is I had water in the lower unit after running for about 10 hours. Changed it to see if the seals would hold (hadn't been run in ten years), still pulled water into the lower unit oil. On the last trip after loss of power it started spitting oil sludge out of exhaust and overheating too quickly. I pulled the lower unit apart and found the inside is in near new condition (no rust, no shavings, no sign of wear). Before that I started and ran it on muffs and it idles, revs fine. Any ideas on what the deal is?

Thanks in advance.

Re: 1971 Chrysler 85 hp Loss of Power

Hi, sounds like the bottom crankseal has gone, backed up by your compression figures, had the same thing on the rebuild i have at the moment, the lower needle bearing has a seal pressed into the bottom, this goes and the cylinder looses power / compression, allowing the carb to run "lean" as it is pouring the fuel / oil mixture to leak out into the exhaust track, The seal cost me ?3 ( US$ 4.79 ish ), you have to pull the powerhead and remove the spacer plate and split the crankcase to replace it, so thats why i decided to rebuild complete as you are stripping it that far, you might find that the bottom piston is also scored due to lean running.

Re: 1971 Chrysler 85 hp Loss of Power

Wow, thanks.

That sounds like a project, but I agree if I am tearing it down that far at least a semi-complete rebuild would be worthwhile.

Re: 1971 Chrysler 85 hp Loss of Power

Hey searay-- How much power loss are we talking about. At 137 PSI, you should not notice that much. Check the timing 32 BTDC, the distributor cap, the points at .014 or .016 open (--check the manual, I forget), and the wires.

These 2 cycle engine cylinders go to atmospheric pressure at the bottom of the stroke because both bypass and exhaust ports are open. THUS: Crankcase compression and position of the carb butterflies will not affect compression ratio. Before you do anything else, pull the head and check the head gasket. While open, check the cylinder for scoring. If it is OK, next step would be to try a decarbon treatment. If that doesn't do it, then pull the exhaust cover (careful--bolts are old and corroded some will snap and need to be drilled and tapped). Check the piston and rings through the exhaust port to see if there is some aluminum rub-off or carbon holding the rings compressed on the low cylinder.

Now: As to your lower unit, you need to replace the water pump impeller and possibly the pump body if it is in poor condition. The three most likely leakage places are 1. The fill and drain plugs. Be certain they are really tight with new gaskets. 2. The rear bearing carrier seal (behind the prop) Two allen head capscrews hold this carrier to the gearcase torpedo.and 3. The drive shaft seal under the water pump.

That is a 2 piece lower and there are small O-rings under the bolts that hold the gearcase torpedo to the midunit. There is also a large O-ring in a groove around the gearcase torpedo.

You can buy seals and other parts from franzmarine@aol.com

Re: 1971 Chrysler 85 hp Loss of Power

Thanks Frank,

The timing was one of my initial thoughts too. I haven't checked yet because I have it torn down to replace the water pump impeller, pump body, and drive shaft seal.
Any advice on replacing the drive shaft seal?

Re: 1971 Chrysler 85 hp Loss of Power

Ohhhh! thats a tough one for me. It's been a long time since I did it.

I think you must pull the drive shaft to replace that seal. The drive shaft is carried by an upper and lower tapered roller bearing. You remove the pinion nut, remove the pinion and pull out the shaft. The upper bearing may slide off the shaft but it will probably take out the seal. The upper is located on the shaft by an external circlip and that does not need to be removed. The pinion is a slip fit on the shaft splines and once you remove the nut, it should come right off.

Once you yank the old seal, it is just a matter of re-installing the drive shaft with the upper bearing and pressing in the new seal. Use an appropriate sized socket and a length of pipe long enough to clear the top of the shaft. Tell you what----Tomorrow I will go into the garage and take a couple of photos of that lower unit--maybe they will help. Edit : Third photo shows the pocket below the water pump mount into which sits the upper shaft bearing and on top of that the seal. The photos show a "three bolt" gearcase. Depending upon the year some were two bolt with the center stud not there. Later models had it added.

Just remember that even these early lower units still had a hidden mounting bolt inside the exhaust snout. Some needed a 5/16 12 point socket to remove, others were standard hex head or allen head bolts.

When re-installing the pinion, since the nut and pinion preload the bearings, you must either use a new nut or re-deform the threads AND you must torque to a specific value--I don't remember offhand but a manual will give it. It might be on the order of 85 INCH pounds. Certainly not a lot.

Usually the pinion nut is "staked" on three of the flats. You have the option of re-staking with a punch OR you can squeeze the nut slightly oval in a vice. Note slightly-- if you get it too oval, it will not thread on the shaft. You just want to deform it slightly so it will not back off the threads.

Do not modify or sand the two case halves to clean them up. They set the pinion to gear tooth clearance and if you change it, the backlash will be too tight-- you will eat up the gears while running.

Re: 1971 Chrysler 85 hp Loss of Power

Frank, that is great info.

I have it down to just the upper tapered rolling bearing left on the driveshaft. The bearing is rusted but semi-functional. I am going to replace it before I put back together. I don't own the tools to accomplish this so I am thinking of having a boat mechanic I know do it for me. Since it is not a terribly hard, long job I thought I might have him do the new upper tapered rolling bearing, oil seal and install the lower tapered bearing/gear/pinion nut assembly (assuming it will be new or re-formed/staked). What do you think the price for this should be?

All replies are welcomed and appreciated.

Thanks,

Nick

Re: 1971 Chrysler 85 hp Loss of Power

Around here, marinas get about 100-110 bucks an hour. If your mechanic friend is working for himself, slightly less.

It should take about an hour to do the work needed since you already have it apart

Re: 1971 Chrysler 85 hp Loss of Power

Ok, so long story as short as possible, I had the bearing replaced and put the unit back together with new seals, impeller, pump housing, bolts, etc. It looked to be great but I had trouble with shifting, i.e. would not go into reverse or neutral properly. Tinkered around a bit and then figured out I was being stupid and forgot that the shift shaft was a bolt that screws in and out. It had worked itself out and needed a couple of turns back in. That solved the problem and would have been the easiest/fastest if I had thought of it first. The lack of power and oil/fuel junk spewing from the exhaust seems to have been rectified by my replacement of the ignition wires, in concert with cleaning of the distributor. I have not had a chance to water test it yet but it is great on muffs.
I will update on how the test run goes.

Nick

Re: 1971 Chrysler 85 hp Loss of Power

Nothing good to report.
I have spark on cylinder 3, changed plugs and it seemed to fire better. Cleaned the carb (which made it fire occasionally),; could I have accidentally changed the firing order? Now it is 1, 2, 3. 3 is the one that has spark, fuel, and air but mostly is dead. Also it has started to hesitate and/or stall at medium rpms/throttle. It is better at WOT, and will plane off with a light load. Any ideas, timing, firing order, plugged carb, no idea? Still has only a 10% loss in compression which I can't believe is the real problem.

Thanks

Re: 1971 Chrysler 85 hp Loss of Power

Plugs burning right?Post a pic.Water in the gas?
The head gasket could be bad(even with good comp).
Clean the carb.Install a particle filter between the pump and the carb..Wal-mart B2 or B12 something like that.One is for the 1/4" and the other for 5/16" hoses.

Re: 1971 Chrysler 85 hp Loss of Power

Firing order is 1,2,3 and top cylinder is #1. Assuming your engine has the Motorola magna-power (large black aluminum finned box) then if you are getting spark on the other cylinders AND the spark is not continuous then the Cd box is good. By continuous I mean that when you turn the flywheel by hand, as one plug sparks, if you hold the flywheel in that position, it will only spark once, not constantly, like bzzzzzzt. be certain that the distributor is set to #1 cylinder at top dead center. The pulley on top has a circular groove and pointer line to match the flywheel curve at TDC.

Since you have cleaned a carb, I suspect that you had removed it. At this point, remove all three, disassemble them and clean them well. Then re-mount them. Use the sticky under FAQs Synchronizing timing and carbs to reset them.

Post a couple of photos of the complete engine and ignition if possible.

Re: 1971 Chrysler 85 hp Loss of Power

Re: 1971 Chrysler 85 hp Loss of Power

I'm going to pull all the carbs and clean them.
Quick question (hopefully), my choke doesn't work, which is fine because it starts and runs fine without it, and I was wondering if there was a way to fix it while I'm taking it all apart and cleaning everything?

Thanks for any help.

Re: 1971 Chrysler 85 hp Loss of Power

Looking at your photos, it appears that your throttle cam is not correctly adjusted. This may prevent the throttles from opening fully, explaining a "loss" of power. Read the sticky " synchronizing carbs and timing " In the FAQs at the top of the forum.

A non functioning choke can be due to several factors:
1. Broken or shorted power line or bad ignition switch. Check that there is power to the choke when the key is depressed in start or run position. Check that the terminal is not touching the solenoid strap.
2. front carb gaskets on the airbox have swelled, jamming the choke lever stops closed. Either carve out the offending part of the gaskets or bend the stops a little more to clear them.
3. Solenoid plunger is stuck. Remove the solenoid and clean any varnish from inside it. Then clean the plunger. No lubrication is necessary here.
4. Choke butterflies are stuck. If you can not move the chokes by hand, then the butterfly shaft(s) are varnished or corroded in the carb casting.

Re: 1971 Chrysler 85 hp Loss of Power

Cleaned the carbs, reinstalled, now the issue is that the whole thing won't shift from being advanced back to low rpm position. Going to check the power to the choke solenoid, could I just have a bad solenoid? Nothing is stopping it from moving. Not too worried about this issue but if I can fix it why not. Why would the assembly not turn back into position when the throttle is pulled down? Cable adjustment, shift shaft adjustment, ?????

Re: 1971 Chrysler 85 hp Loss of Power



Well, going back, I noticed that in the second photo, BOTH your control cables are installed incorrectly. The groove needs to be retained by the dent in the clamp. The black rubber covers should be back against the clamp if the cable is positioned correctly.

Now. You also need to check the large throttle cable terminal. If it is not adjusted so the center is pulled out about 3/16 to 1/4 inch with the engine in neutral, the you will have throttle return problems.

Lastly, check that the distributor moves freely in its mount.

Re: 1971 Chrysler 85 hp Loss of Power

Thanks Frank.

I fixed the cables. Now everything is moving smoothly and feels really good. I synched the carbs and now need to set the timing to 30 degrees before top dead center before I take to the water for final carb adjustments. How do I do this?
I am attaching pictures, if anyone see's any problems please let me know.

Thanks.

Re: 1971 Chrysler 85 hp Loss of Power

Remove and ground all three plugs. Set the control handle to forward gear, wide open throttle. Turn the ignition switch to run position. Now turn the flywheel by hand until the top plug fires. See where the flywheel mark is in relation the the block pointer. Adjust with the screw and two black plastic blocks on the distributor. Widening the gap between the blocks advances timing, closing the gap retards timing.