Volvo V8 300 C-A overheating issue (5.7 injected engine)

gferdon

Recruit
Joined
Dec 31, 2010
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1
Just a heads up for those of you who may have experienced this problem. My Boat is a 2013 Cobalt 232 with a Volvo Penta V8-300 C-A DP power package. The boat's been is service for 3 seasons and never had any issues (200 hours). On several occasions we have failed to secure the fresh water flush hose cap and noticed a check engine warning and resultant overheat condition. What I didn't realize was each time this happens the raw water impeller, mounted on the front of the crank pulley, runs dry and suffers damage. When you realize the cap is off, you simply tighten it and, usually, the problem is resolved (or so you think). The fact is the impeller is then on borrowed time.

In any case, the last time this happened tightening the cap did not solve the problem and we limped back to the ramp. Changing the impeller ( the old impeller was about 2/3 missing) was very easy and inexpensive (about $50.00 for the Volvo kit). However, once the impeller was changed we had a problem with the check engine coming on and a large fluctuation in temperature. That is, it would vary between 154 deg and 175 deg every few minutes. I was puzzled by the check engine warning since it's not supposed to activate until 195 deg. Long story short, I removed the thermostat housing (very easy on a relatively new engine) and found most of the old impeller blades were jammed in the smallest hose nipple on the housing. I cleaned out the debris, changed the o-ring and gasket, reassembled the housing and it ran perfectly. The stock thermostat on this engine had a 150 deg value and will run at 160 deg +/- 2 deg under all conditions. Upon further research, it seems the reason I was getting the check engine warning was due to low water pressure in the block. My speedometer digital readout does not have the capability to display that fault but will show the check engine light if it exists (very confusing). I am considering getting the complete Volvo digital panel which will show all faults. As usual I am a bit wordy here but hope it may help.

G-
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
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47,309
Common problem with missing impeller blades
 
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