Hot Exhaust Manifolds

[shoot_my_boat]

Hey<br /><br />I have a 72 Ford 305 5.0L with a Volvo Penta 270 & my exhaust manifolds seem pretty hot. I checked the water pump & it seems ok. I also installed a 150 degree t-stat. My temp guage goes erratic at some points as well. It will go from 140 or lower to 180 immediately. The temp sensor looks good. If it matters, all this has been done in the driveway.<br /><br />Also my idle is a little high. I'm a FI person not a carb. How would I go about adjusting it?<br /><br />Does anyone have any suggestions?

 

[wvit100]

Re: Hot Exhaust Manifolds

140 degrees or there-a-bouts will hurt to hold your hand on but it won't actually burn you. Anything hotter than that will burn your skin if you hold it there. Hold your hand there for a minute and see what happens. Or you could use a thermometer and check it. 180 degrees for the motor temp doesn't seem bad.

 

[mathiasmorgan]

Re: Hot Exhaust Manifolds

Not trying to insult your intelligence, but you are running this in the driveway with water attached right??? <br />If you are... excuse the question.. but I've seen it done many times before.. lots of damaged engines from running them dry.. Especially love the "Well I only ran it a few minutes" guys.. <br />George

 

[shoot_my_boat]

Re: Hot Exhaust Manifolds

Yeah, I'm running off a hose!<br /><br />I havn't been a member here too long, but I read that the manifolds should be fairly cool to the touch. My question is will they run cooler in the water since i'm sure the pump would pull more water in or do I have a problem? I just finished putting it all back together & would perfer if I didn't have to get towed in on the first day out. Any suggestions about the guage jumping? Is this a sign that it's goin bad or a short somewhere in a ground?<br />Thanks!

 

[mcpo]

Re: Hot Exhaust Manifolds

Exhaust Manifolds should normally be hot to the touch although I'm certainly not an expert. But, 180 degrees is not too unusualy. When you get around 200 you need to stop and check the impeller or water pump. 200 is a bit too hot for most engines. 160 is perfect, but I've always been told that stern drive engines run hotter (around 180).<br />As far as your guage goes...it is either shorting out on something or is going to go bad. Changes in temperature shouldn't make it pop around (jitter) as I understand you are saying. You might also check the temp sending unit on top of the engine that goes directly to your guage...it could be going bad and this most likely the problem.<br /><br />I have a question about the small black wire coming out of the Distributor Cap (attached inside it where the points/condensor are connected. Does it go to the negative or positive side of the coil?<br /><br />Thanks..

 

[ed hobbs]

Re: Hot Exhaust Manifolds

I agree with mcpo - check the sending unit and trace the wire coming off it. Look for worn insulation that could be grounding it against the engine. Mine was bad in the main harness, and I had to reroute a new wire around it.<br /><br />As for the hot exhaust, the hose feed could be the problem. Figure you have a 1/2" garden hose feeding your system with 3/4" or larger hoses; no way you can get enough water. I recently put brand new exhaust manifolds and elbows on. When testing in the driveway, one side ran hot and the other ran cool. That was irritating! I came to realize that I had cut a wire tie that was holding the hoses together, and the hose that went to the port manifold was about 4" higher than the other side. Since there was not enough water to supply both sides, it all ran downhill to the starboard side. Even after tieing the hoses back down and testing again, the temperature fluctuated because of the limited water supply. Hope this helps!