Running Hot on The Muffs, Troubleshooting advice needed.

[R. Wood]

'84 1.6l OMC Sea Drive (4cyl. 115hp Crossflow)<br /><br />One of many issues discovered today on my pair of Sea Drives!<br /><br />Here we go............<br /><br />Reman'd power installed last year, with typical bells and whistles (rebuilt carbs with upsized idle air jets to go along with Boyseen power reeds, new recirc valves, new 4 wire VRO, new p-packs, coils, new s-plugs and wires, new voltage regulator, new water pump kit, t-stats, hoses, etc,)<br /><br />Ran like a champ @ temp last year, although RPM appeared a little low (4500 - 5000), which after much discussion attributed to bad tach, bought tiny tach to troubleshoot but didn't get that far. <br /><br />Today fired her up, took a few tries but attributted that to fogging last year, once she was up and running ran and sounded well on the muffs, tell tale strong, (but cold?), water pressure OK for muffs @ 5 psi plus. After a few minutes got hot horn. Heads (both) running hot by touch, Infared pyromter acting flaky (figures!) but also indicated hot (160+). Did have lower units off but thought re-install went OK (good tell tale flow). Also checked spark and compression. Spark good compression @ 120 - 125 on all $4.<br /><br />We seem to have repeated overheat issues with the pair of Sea Drives we have. Last year,other motor ran hot on the muffs, re-installed new stats and was OK, but fried voltage reg, replaced this year and ran OK on muffs but found # 3 cyliner with low compression (topic of another post).<br /><br />Frustrated with my money pit and tried of making mistakes. Please help!!!!!!!!!!!!

 

[DJ]

Re: Running Hot on The Muffs, Troubleshooting advice needed.

R. Wood,<br /><br />I don't trust crossflows on the muufs. They act weird.

 

[OBJ]

Re: Running Hot on The Muffs, Troubleshooting advice needed.

R. Wood....you run in salt or fresh water?<br /><br />If you run in salt, ya' might have some sodium(salt) built up in the passages. If ya' run in salt, flush the engines out with fresh water at the end of the day........if possible.<br /><br />Little concerned about the 5psi on muffs. You should see a little more than that if your hose pressure is good. You see this on both engines?

 

[ob]

Re: Running Hot on The Muffs, Troubleshooting advice needed.

(once she was up and running ran and sounded well on the muffs, tell tale strong, (but cold)<br /><br />Was this after the engine was warm and running?This may be a clue to your problem.Tell/tale should feel warm after the engine is up to temp.

 

[R. Wood]

Re: Running Hot on The Muffs, Troubleshooting advice needed.

Thanks for the prompt replies.<br /><br />I'm always nervous about running on the muffs, but didn't have this issue last year during shakedwon of this same motor. Port motor ran today with same set up and didn't overheat (worse issues found!). Even with that said should I consider trying to fab up some sort of tank?<br /><br />I don't run in salt water. Boat is ran in Lake Erie, (maybe sucked up some muck?). Replaced water intake screens in lwr unit last year also, still looked clean and intact but will double check.<br /><br />Regarding the water pressure PSI, I think we saw about the same on the port before we pulled her. Always see a signifcant increase in water but din't make it to find out.<br /><br />Had cold water from the tell tale during warm up and right before hot horn (like stats not opened?). Both heads hot to touch. Last year's problem on port motor was one side only and corrected with removel / re-installation of stats.<br /><br />Would venture to guess unlikely for both stats to stick(?) causing both sides to run hot. <br /><br />Of note (or not)boat it stored outside during SE Michigan winter, is there the potental for trapped water to (?). <br /><br />Where to next? Remove and check stats or ?<br /><br />As always inquires and suggestions welcome, actually may prevent costly therapy!

 

[Solittle]

Re: Running Hot on The Muffs, Troubleshooting advice needed.

You mention a pair of SeaDrives - Are they both acting the same way?<br /><br />Did you replace the deflectors?<br /><br />P.S. I have a pair of 87s.

 

[R. Wood]

Re: Running Hot on The Muffs, Troubleshooting advice needed.

Hey So Little,<br />Glad to see you jump in, I know you've had your fair share of issues with your pair of Sea Drives! I hope your doing better than me! If I recall correctly you suffered from water ingestion issues on one (or both?) of yours.<br /><br />On and off overheat conditions since we bought her, mostly on the muffs. Did overheat badly on the lake a few years back. For which I'm pretty sure lead to or contributed to head gasket failure and then piston failure (and crank damage for that matter). P-Head replaced with re-man'd and ran great last year (although a little under on RPM, but speculate tach)<br /><br />Didn't have any issues on the lake last year, everything seemed to be worked out.<br /><br />To the point, I only had overheat on 1 of the 2 motors today during shakedown.<br /><br />All,<br />For what it's worth I know boat was orginally purchased in Florida, but from what I was told boat has been in Lake Erie since '88 or so.

 

[R. Wood]

Re: Running Hot on The Muffs, Troubleshooting advice needed.

I haven't had a chance to troubleshoot yet, but after pondering the situation and the comments here, OBJ's post rang a bell. <br /><br />Last year when pulling out, I fogged in the slip used to pull out. I recall water being low and kicking up a signifcant amount of silty / murky water. <br /><br />After doing some research here in the archives, I came across a post by Rodbolt regarding modifcation of the t-stats. He noted "that a vent can be added to the poppet", and later commented "that sand in NC is bad about clogging them up". The post also mentions modifcation of the vent hole in the "phenolic t-stat housing to 1/8" or 3/32"'s".<br /><br />I'm guessing I may have sucked up enough "stuff" to block vent in phenloic block. Coupled with the difficult installation of the assembly, I specualte that it could also be partailly blocked with gasket sealer (or gasket itself) during install as everything slides around (?). <br /><br />For clarity the vent holes (one per side?) are located in the lwr center (?) of the phenolic block (hard plastic block between lwr mid section and t-stat hsg).<br /><br />Regarding the t-stats mod, can someone clarify location and size of hole to be drilled.<br /><br />Are these mods the way to go? The design seems to "lack robustness" to clogging. If I understand things correctly the vent holes (and holes to be added to stat) allow hot water to get to the back of the t-stat to pop it open(?). Shouldn't the relief valves allow enough flow to get behind the t-stats to open them? Can the problem be exaggerated from the lwr pressure provided by the muffs?<br /><br />Sorry to be long winded, it's the engineer in me!

 

[R. Wood]

Re: Running Hot on The Muffs, Troubleshooting advice needed.

^

 

[Solittle]

Re: Running Hot on The Muffs, Troubleshooting advice needed.

You might try dropping the lower unit and taking the cover off of the t-stats & backflushing via the pick-up tube. You can do this when you fuss with the poppets.<br /><br />I have also heard, but have no experience with, water passage clogging behind the exhaust cover. The beware on this for older motors like ours is bolts snapping.