1993 90hp Force Overheated! Rebuild or replace?

[mitchbuck]

I have had a spurt of engine problems lately with my 1993 90hp Force and I am trying to figure out whether to repair or replace the engine but would appreciate some input. First some Background.

My engine overheated last night to the point where it smoked terribly and the block became extremely hot. Luckily I was able to turn it off before anything bad happened and got a tow in. However, I did hear a pop followed by a liquid spray at one point which I have no clue what it was. A visual inspection of the block didn't reveal any issues, but I took it down to have a professional set of eyes survey it. What they found was that the water pump housing was cracked, but no further damage. They were able to get the engine running and they don't think there is any further damage beyond that pump. However......

I have another thread on here with some issues regarding the "engine bogging down trying to get up on plane". It doesn't happen all the time, but only sometimes after the engine is hot and been off for short period of time. Anyways, the problem persisted after replacing the fuel lines from the tank to the fuel pump & carbs, fuel/water separator, cartridge filter, rebuilt the thermostat and fuel pump, adjusted engine timing, replaced battery, spark plugs, and lower unit oil. In the past week the engine has become hard to start and required me to push the throttle all the way forward in neutral just to get it started. What has me concerned is that I replaced the fuel lines earlier in the year because they were rotted to the point where little bits of hose were getting to the fuel pump (however before the inline cartridge filter) and I installed a fuel-water separator after I observed this. My mechanic said the rebuild would be about $100 in parts plus labor but warned me that he has performed a couple of carb rebuilds (due to debris) where they could not revive the engines and ended up having to replace the carbs themselves! I know that these carbs are not made anymore and I tried looking for them online without much success.

So I am trying to figure if it is worth spending the money to replace the water pump and rebuild the carbs (not including any unknowns) after the engine overheated. My questions are:
1) Is there anything else that i should be concerned about after the engine overheated? Head gasket?
2) What are the chances that the carbs could not be rebuilt and instead need replacing? Is the mechanic giving me a line about carbs becoming completely shot?
3) If the carbs are shot, how difficult is it to find a replacement set of carbs for this engine?

Thanks in Advance.

 

[jerryjerry05]

Re: 1993 90hp Force Overheated! Rebuild or replace?

I've NEVER seen a carb need replacing unless it's been soaking in salt water or so corroded it sucks air.
Most can be rebuilt.
All the parts are out there.
Take them apart and post some pics??
Yours are working and probably need just to be set up right.
Maybe look for a new mechanic too??
Just wondering does the mechanic have a motor just laying around that he's willing to sell to replace your junker???

Unless the piston cylinder is so bad, these motors are easily rebuilt.

Profile,location?

Send it to me,I'll rebuild it for you.

 

[mitchbuck]

Re: 1993 90hp Force Overheated! Rebuild or replace?

Thanks for your input. To answer your questions I am located on Cape Cod, Mass. I'm scared to take the carbs apart at this point, especially because it sounds like they are in rough shape and I've never done it before.

 

[jerryjerry05]

Re: 1993 90hp Force Overheated! Rebuild or replace?

I'll bet ya there aint nothing but dirt in there??If that??
These carbs are simple and easy to work on.
If taken apart and you don't try to adjust anything they can be put right back together.
Clean in soap and water or carb spray.
I use soap/water and then blow dry asap!!
Post some pics??

If they are in that rough a condition you can't hurt them any more.
There is a post,top of the Force Forum.
Called a linc/sinc.Do that after you clean the carbs.
Inital setting on the air screw is 1 turn out.

 

[Jiggz]

Re: 1993 90hp Force Overheated! Rebuild or replace?

After last night's overheat do you know if your mechanic has done a compression test? What were the results if he did?

 

[mitchbuck]

Re: 1993 90hp Force Overheated! Rebuild or replace?

I received the results of the compression test today. The three cylinders were 130, 130, and 100. This has me concerned since this exceeds that 10%. How bad is this? Are we talking a need to rebuild the head gasket and/or rings right away?

 

[roscoe]

Re: 1993 90hp Force Overheated! Rebuild or replace?

I would pull the head and inspect for damage to the gasket, the pistons, the cylinder walls, and the rings.

If all internals look good, then just put on a new head gasket and get to working on the carbs and water pump..

If there is internal damage, then it is time to reassess.

 

[emoney]

Re: 1993 90hp Force Overheated! Rebuild or replace?

I'm surprised your mechanic didn't do a compression test first. When they get that hot, it's common for the head gasket to need replaced, which could be the source of your low compression on one cylinder. Usually, when there are bigger issues, the low cylinder won't have #s as high as yours, but as Roscoe said, there's only one way to know and that's to take a look. I'm with Jerry in the "maybe it's time for a new mechanic" comment. I've seen carbs from 40 year old motors (used in salt water) that were rebuilt bad to factory spec. Takes an awful lot to have one need replaced. Spend some time here in the forum reading threads about carb cleaning & head gaskets so you can be familiar with what's taking place. I've found over the years that the repair needs of my outboards (or anything for that matter) became a LOT less daunting when I understood what's taking place. Knowledge is power, as they say. Plus, it's always better to be informed when depending on someone else to do the work. Otherwise you can easily fall victim to someone that's lazy and/or looking to make a quick buck. Not that this person is this way, but there have been some that would sell you a "rebuilt carb" because it's quick and easy and they just take yours off and rebuilt it for the next guy that comes along. I repeat: Knowledge is power!

 

[Davetward]

Re: 1993 90hp Force Overheated! Rebuild or replace?

For what it is worth, and if you are so inclined, read all that you can on this and other forums and go for it. It is not rocket science!! And, the knowledge you will gain will never be wasted. If the worst happens and you wreck the block or something else (actually, highly unlikely) you are no worse off than ditching the engine. As for carbs.. almost always repairable. Good luck and more importantly, have fun!

 

[mitchbuck]

Re: 1993 90hp Force Overheated! Rebuild or replace?

Update...

So I had the shop replace the water pump and rebuild the carbs even though compression was low in one cylinder. While replacing the water pump they realized the waterline was broken, but in order to replace it they had to remove the powerhead (covered in another thread). After this was done I took the boat out on the water but ran into issues as the engine wasn't timed/synched properly by the shop. After the shop readjusted linkages, the boat ran fine for an hour or so before I ran into more issues. The engine wouldn't run more than 1500 rpms and I believe that I was getting engine knock (faint low-pressure intermittent booming sound) in addition to strong vibrations. The compression was rechecked and the bad cylinder was now at 40psi.

So I have a plan moving forward, but need some advice on it. I am finally going to pop the head off the block so that I can inspect the rings, pistons, and cylinders and have the Clymer and SELOC manuals (and you guys!). Besides the obvious signs of damage such as scratches/scouring, what should I be looking for to determine whether the pistons/rings needs replacement or cylinder honed? Is there a way to test the engine to see if I just need a new head gasket? If I need to replace the pistons/rings, do I have to completely remove the powerhead? Thanks!

 

[Jiggz]

Re: 1993 90hp Force Overheated! Rebuild or replace?

It's amazing your mechanic continued to insist the engine is OK even though it's obvious it wasn't as indicated by the low compression reading! Now the situation has gotten worse than before. The only way to find out if you need a new head gasket is to remove the head and do a visual. Do your wallet a favor and do the following:
1. remove and inspect the head and gasket. If gasket is looking good, take no chances and replace it anyways.
2. Inspect the cylinders, any cylinder with signs of scoring, needs further inspection by removing the pistons. There are many threads in here detailing procedures for removing the pistons without disassembling the power head.
3. Measure the scoring to see if you need to just hone or re-bore the cylinder. If the scoring is not that deep barely catches with fingernail, you can just hone the cylinder. If it's to deep a re-bore might be in order. Unfortunately, a re-bore will be more expensive.
4. If it only needs honing, a honing kit cost around $25. You will need a bore gage to re-measure after honing to get the proper piston size.

This is all for now. Re-post after all your visual inspection is completed.

 

[mitchbuck]

Re: 1993 90hp Force Overheated! Rebuild or replace?

Thanks for the input jiggz. Its really my fault, not the mechanics, as he warned me and I was just hoping that after rebuilding the carbs/water pump that I could use the boat a few more times before the season ended and then address the head gasket myself in the offseason.

Anyways, after I remove the head and perform a visual inspection I will definitely post pictures! I was planning on replacing the gasket either way. Should I use heat and/or chemicals to loosen the bolts on the head?

 

[mitchbuck]

Re: 1993 90hp Force Overheated! Rebuild or replace?

UPDATE: So I was finally able to remove the head last weekend with my buddy. We were surprised because the bolts were eerily easy to remove with a regular socket wrench. When we popped the head off we immediately noticed that piston #3 (bottom) was bad but #1 and #2 were good. The #3 piston had signs of pitting and melting on the piston head and some of the piston edges were deformed as well. The cylinder head also had some signs of pitting on it, but the other two were fine. I was surprised because the cylinder walls were very smooth with no scratching/pitting that I could see or feel.....except that the bottom cylinder had a large gouge towards the top of the cylinder The gouge seemed rather deep....you could definitely catch your fingernail in it and it was probably 1/4" long. However, the gouge didn't look fresh as the edges were rolled/smoothed out, so I don't know what to make of it. I have uploaded a video to youtube and I apologize about the low res as it was taken with a gopro.

So I am trying to access where I go from here. I know that I need a new piston/rings in #3. I am not sure whether the #3 cylinder needs to be honed or bored or not as the walls are very clean except for that one gouge.

 

[Frank Acampora]

Re: 1993 90hp Force Overheated! Rebuild or replace?

The damage you see on the bottom cylinder and cylinder head is from detonation due to lean running. No matter what you do--hone only or rebore-- definitely remove all carbs and disassemble them. Then do a thourough cleaning. Set them up according to the FAQ sticky: Synchronizing carbs and timing.

From the video it is difficult to really asses the damage. However, if the cylinder had 100 PSI It can't be too bad. I would first hone the cylinder to see if the damage is removed. Then mike the bore to see if it is still within tolerance (+ .002 over max.) If it looks good, then buy a piston. ( In fact, for testing purposes, if the rings on the damaged piston are not worn or broken, it could be reused--just to see if compression comes up with honing)

If the cylinder still shows damage or if it is out of tolerance, then bore it and buy an oversized piston.

HOWEVER I can not stress too strongly: The damage is a symptom of fuel problems. Be certain that the fuel system is 100%. There is no sense in rebuilding an engine only to destroy it again relatively quickly.

 

[mitchbuck]

Re: 1993 90hp Force Overheated! Rebuild or replace?

Thanks for the fast reply Frank! I am getting my buddy to upload a better quality video tonight (hopefully). Unfortunately we didn't check the tolerances of the cylinder.....totally forgot. The cylinder was at 100 psi after it overheated initially, but is now at 40 psi after the shop worked on it. The shop rebuilt the carbs after it overheated, and they said that they were a mess. However, when I got the boat back the linkages weren't hooked up correctly and the motor ran like crap, so I had to take it back to have them redo it. After they fixed it, I ran the boat for an hour the engine started running really rough (almost sounded like low booming sound was coming from engine and I got a lot of vibrations) and wouldn't get up on plane. After rechecking the compression it had dropped to 40psi. In regards to the fuel problems....I have new fuel lines, fuel pump, fuel-water separator & cartridge filter on the engine, and have a 12 gallon portable tank in addition to the below deck tank....so the only thing I can point at is the dirty carbs. Could bad synching/timing have contributed to detonation at all (aside from overheating & dirty carbs)?

 

[Frank Acampora]

Re: 1993 90hp Force Overheated! Rebuild or replace?

Poor quality fuel OR timing too advanced can cause the problem. Ignition advance at wide open throttle should be 30 degrees. At 40 psi I would bet that there is enough damage to need a rebore. I would be surprised if honing removed the damage.

Do yourself a favor: Unless you are all thumbs, do the work yourself (with the exception of the boring) A mechanic is (as you probably already know) going to charge you a LOT for simple jobs you can do yourself with hand tools. AND--I don't trust a lot of mechanics to actually know Force engines. Mind you, I am not "dissing" Mechanics in general, there are some very good ones out there. In fact, the guy you used was apparently responsible and you ignored his advice. But on the other hand, you say that the linkages were not correct and that is a point against him.

 

[okbayliner]

Re: 1993 90hp Force Overheated! Rebuild or replace?

force motors are very simple I do all work on mine myself and if I can do it anybody can

 

[mitchbuck]

Re: 1993 90hp Force Overheated! Rebuild or replace?

My buddy reloaded the video in a much higher quality in the above link. My biggest concern is the big gouge which you can see in the bottom of the bottom cylinder.

Frank, I will definitely do the work myself if I choose to proceed. A lot of shops didn't want to touch the Force engines and the mechanic I had work on was a Merc guy but still didn't have experience with Force.