1999 Challenger 1800 twin 787 Engine problems.

[RTC]

Hi everyone, this is my first post on here... Could really do with some advice.

Me and my friend purchased the boat a few months ago and we are having some real problems with the left hand engine.

we have had it started a couple of times... however the engine was back firing and would not idle without stalling, since then we have had the carb off, cleaned it, all the needles and diaphragm's seem fine.

we've checked the timing on the rotary valve which also seems to be good, as well as removing all of the rave valves and cleaning them.

Plugs are sparking okay and fuel is getting in to the engine fine, the battery is new and the other engine works great.

After we've had the carb off and checked the timing we tried starting it again much to no avail apart from it back firing a few times and running for a few seconds (sounded a bit strange when running)

Any help would be much appreciated!

PS: We are going to swap the carbs over on the two engines tomorrow to eliminate any possible carb problems.

Thanks again- Rob.

 

[scski]

Have you checked the compression?

 

[RTC]

Hey, I'm borrowing a compression checker tomorrow... will post the results. thanks -Rob

 

[RTC]

Just completed a compression check on the two engines. the working engine is approximately 125 PSI at both cylinders and the bad engine is down to 90 PSI at both cylinders.

What is the normal pressure for a 787 engine? can timing affect the compression or is it just likely to be piston rings/ head gasket etc?

Is a low reading of 90 PSI likely to prevent the engine from starting/ running or could it be something else?

Again, any help would be much appreciated -Rob

 

[scski]

150 psi is healthy/fresh.

Your 90 psi engine is shot.
Your 125 psi engine is on the way out, assuming the gauge is accurate.

Either two top end jobs, or two short blocks. You could do the bad engine now and other in the off-season.

 

[RTC]

150 psi is healthy/fresh.

Your 90 psi engine is shot.
Your 125 psi engine is on the way out, assuming the gauge is accurate.

Either two top end jobs, or two short blocks. You could do the bad engine now and other in the off-season.

Thanks scski, I think we will do both if that is the case, sorry for being dumb but can i ask what you mean by two short blocks?

Is it an expensive job? and will the engines need to be removed from the boat? Thanks- Rob

 

[Dr Honda]

a "Short block" isn't really the right terminology... but He is basically saying you need a complete rebuilt engine.


Just for an FYI....


a "Short Block" would be an engine with out the heads. (typical on a 4-stroke)

A "Long Block" would be a complete engine without accessories.


A "Top-end" is replacing only the pistons, rings, wrist pins & Bearings, and hone/machine the cyl's.

A "Bottom-end" would be to rebuild the crank, and rods.

 

[scski]

Yeah, not exactly the correct terminology but it's used often here, a rebuilt engine from SBT (Short Block Technologies) is $845 plus shipping and core and includes a 1 year warranty. "Premium" engine with 2 year warranty is more.

You could do just the top end, but the bottom end (crank & bearings) may give you a problem later. You didn't say what year model, but I'm guessing and older one so complete engines may be best.

 

[RTC]

Okay, this is starting to sound expensive... when we bought the boat he started both engines up, and told us it would have a full service before we took delivery. (We don't have a great deal of experience ourselves) when we picked the boat up we took it out only to find it would not start. we took it back to the dealer and he had it for 5 weeks and did nothing to fix the problem so we picked it up to have a look at what we could do ourselves, only to discover that it had not even been serviced in the first place.
.
I think it's time we got our money back.

Thanks for the help guys! - Rob

Ps: It's a 1999 model with twin 787's