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  1. Lou C

    4.3 OMC Cobra Overheating at times

    You’re not cooling at low revs. The impellers do wear you can’t really see it unless you pull it out. If you pull up silt or sand it will score the wear plate which also reduces pumping volume. I have had nearly the same boat almost 20 years and I usually change the impellers every 3/4 seasons...
  2. Lou C

    Impeller housing overheating

    the two piece conversion is a manifold+elbow+90* exhaust pipe & hoses....pretty much the standard Volvo Penta set up used from 1994 all the way up till yjey dded cat converters. It will fit the Cobra perfectly. Firts 2 pics are my conversion last pic shows how it looks from the back side. I used...
  3. Lou C

    5.7 1987 OMC shuts off at Low RPM

    if it drops low enough to starve the igition system yes.
  4. Lou C

    Impeller housing overheating

    In most cases yes especially when you put a load on the engine. However as I said these OE OMC one piece manifolds are somewhat prone to clogging of the outlets because they are on the small side as you can see by the pix I posted. Running on the water hose is not a test of this you need to run...
  5. Lou C

    Mercruiser 4.3 Delco Distributor Question

    Yep the marine Prestolites I have (got 2 spares) all have screens in them. This prevents fuel vapor that gets inside the distributor from causing an explosion or fire. Same as a backfire flame arrestor.
  6. Lou C

    Help with water in oil

    Or even the cyl heads could have rotted through. In any case if the water in the oil is addressed right away the short block may be salvagable. That's what I did with mine.
  7. Lou C

    Part Identification and Schematic Help Needed

    Correct, you never have to remove that plug (that was formerly under the medallion) to drain water, all that is accomplished by removing the plugs on the pivot housing, one on port side (that always should drain water from the water passage in the drive and the raw water hose going through the...
  8. Lou C

    Help with water in oil

    Yes both HGs can fail at the same time if the engine had a bad overheat in the past, which then would let water in the cyls depending on where the gasket blew. The water in cyls would then cause the sticking valves. The water in cyls can also be caused by a leaky rusted exhaust manifold and/or...
  9. Lou C

    Best aftermarket trim sender

    If Sierra makes one I'd try that. What I found on the Cobra units is that the shaft that turns the potentiometer gets sticky and sticks in one position, a little bit of back and forth movement and lubrication with Boeshield or similar and it works fine again. Before condeming the one you have...
  10. Lou C

    Impeller housing overheating

    You gotta get the temp gauge working but for now get an IR temp gun and use that to measure temps. Check: Intake manifold right under stat housing, should be about 10-15 degrees below the rating of the thermostat (standard is 160). Top of exhaust manifolds (elbow section) Mine were usually about...
  11. Lou C

    1992 Mercruiser 4.3 w/ balance shaft and 1 piece rear main seal swap to newer year Vortec.

    The Vortec intake gaskets for sure are different as is the torque spec.
  12. Lou C

    Distributor Cap Needs Frequent Replacement

    Does the design of the engine cover allow water to drip down around the back of the engine? If so try to channel water away from the distributor. I change mine every year due to salt water moorage & salt air....
  13. Lou C

    Best aftermarket trim sender

    Well I don’t have a Volvo but....with the OMC Cobra (similar design to Volvo SX) my OE trim senders lasted about 1 1/2 to 2 seasons max (salt water moorage)...When they became NLA I installed a Sierra one in 2010 and....it still works! So if they make one you might try theirs.
  14. Lou C

    1992 Mercruiser 4.3 w/ balance shaft and 1 piece rear main seal swap to newer year Vortec.

    Interesting so then if someone wanted to put Vortec cyl heads on a pre Vortec block then which ones would they use? Vortec? When I did my overhaul with the pre Vortec Fel Pro sold a kit with the marine HGs, intake gaskets, distributor gasket and the sealer for the front & rear China walls. About...
  15. Lou C

    1992 Mercruiser 4.3 w/ balance shaft and 1 piece rear main seal swap to newer year Vortec.

    Try: Jeg’s Summit Racing Michigan Motorz I’m not sure if the HGs are the same for both...
  16. Lou C

    Question about a 5.0 volvo penta

    Water leaks are unusual on a manifold where it meets the block, they are more commonly seen between the manifold and exhaust elbow. A water leak near the block would make me suspicious that it was really neglected and there could be other problems...rotted head, cracked head etc. look a lot...
  17. Lou C

    2bl vs 4bl

    Just make sure the engine oil is full and your cooling system is good first! The 4bbl is superior above 3500 rpm. When the huge secondaries on a Quadrajet open you will know it by the push in back and the HOWL....and running on the small primaries, it is actually more economical than a standard...
  18. Lou C

    2015 vortec 350’s repower issues

    I think pretty much all I/O installations have anti-siphon valves and when they stick they cause significant fuel starvation problems. So can a clogged fuel vent but I don't think that is so likely, but it for sure can happen. The mechanical pump, I feel is more reliable than electric pumps in...
  19. Lou C

    1990 5.7. 260 Overcooling at idle.

    All it takes is a small flake of rust to hold them open, it happens all the time with raw water cooling/cast iron engines.
  20. Lou C

    Mercruiser were 4.3 MPI first run of the season question

    I started doing pretty much all my own service in 2007 when I bought a drive jack & alignment tool. I figure drive service R&R yearly is about $500 so already saved $7000 on drive maintenance over 14 years. Despite the not great rep of OMC I have found the Cobra very easy to service, esp for the...
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