454 Crusader- one hot manifold- updated --problem solved

[davescarrs]

1987 Trojan Int Express with twin 454 FWC Crusaders. The boat has always been in fresh water (Great Lakes). I've got IR temps on thermostat on both engines around 160 degrees. One manifold is getting hot-220 degrees. The other three manifolds are all 160-180 degrees.

One engine seemed to be running a little warmer and steamier last year so I:

* took trans/oil cooler out along with heat exchanger took them to radiator shop and they were given an acid bath

* Replaced original risers/elbows with new ones.

*Changed intake hoses.

*Impellars were replaced last year and the ones I removed looked great. i also put new cams in the raw water pump.

Not even sure if the manifold was running this hot before i did the above listed work. I'm gonna check the tabs on gaskets to make sure I didn't screw the order placement up.

Also, I noticed a little leaking from the brass stem of the water intake filter jar. So there could be air getting in, but if there was a restriction on raw water side, wouldn't the engine be hot everywhere and more so on the risers/elbows/exhaust hoses etc? Regardless, I'll be fixing that ASAP, but am getting frustrated. Would the thermostat be the next thing to do?


Everything past the manifold has been replaced (FWC adapter, riser, upper and lower elbow):



Can anyone direct me as to where to go from here or help pinpoint an area of concern?

[Allen Sr]

Where are you taking the temp readings at? On manifold or the risers and elbows? Sounds like it may be a blockage in a riser or elbow to me.

[davescarrs]

The risers and elbows are brand new. I installed them two days ago. I've taken temps everywhere (risers,elbows, exhaust hoses, block, stat,etc) with the IR gun. The risers and elbows are about 80 to 90 degrees. They are raw water cooled. There is a block off plate seperating the FWC and RWC right after the FWC adapter (part with hose going to heat exchanger).

I got in narrowed down I think. I think I have to isolate the manifold and back wash it. Maybe some blockage in there? I've read that a FWC manifold should be trouble free, but at this point I may be buying a new one, which makes me nervous looking at those rust bolts holding it on.

My hypothesis is somewhere between the thermostat and the exit out of the rear of the manifold to the heat exchanger there must be blockage.

[BobCT]

Dave,

You should post this on the Crusader engine forum, there are a few guys who know this stuff inside and out. For what it's worth, I replaced my FWC manifolds when I first got the boat and they were fine. I would be really surprised to find that it is the issue.

If you go that route, I got all four off w/o any trouble. I would do the thermostat next, it's cheap and easy and not a bad thing to do anyway. Maybe it's only partially opening and allows enough coolant/volume for one manifold. I would say the "closer one" but the thermo is right in the middle of the engine.

Just a thought, I tend do develop a "here's what it's not" list when chasing a problem and use it as a reason to replace stuff that's going to fail at some point anyway.

Bob

[Big D]

I'm getting conflicting statements in the posts on FW or RW cooled manifolds. I suspect they are FW cooled manifolds. You may have a manifold issue, you should also check your coolant hoses and ensure none have collapsed internally. Before removing the manny and sending it out, there was a product mentioned here before for cleaning manifolds without taking them off; disconnect hoses, drain manifold, pour the solution in, and let sit then rince. Worth a try first. Can't remember the name of the stuff...anybody?

[davescarrs]

Well- after all I've done to eliminate any overheating and then to see that one manifold go way up in temp after all my work almost made me sick!!! However, I read at a Crusader forum (Thanks BobCT- when I posted the problem I was definitely hoping for a reply from you-- I read your reply and checked out the forum, which lead to my problem being solved!!)

Anyway, seems I had an air bubble in that manifold after refilling with antifreeze. I let her run at idle for a bit and saw the manifold getting into the lower 200's--the others were 170 degrees. As I began to start overheating and thought I may blow a gasket... suddenly, she cooled back down and stayed that way. seems it may have been an air bubble trapped in there. She running great now..still have to take her on test ride, but all appears to be great!! Nice and cool.

Thanks for all your advice. Big D- they are definitley FWC on my boat

[BobCT]

nice and you have to love the cost!

I've had that happen a bunch of times on car engines after opening up the cooling system, higher RPM's with heat on does the trick.

Glad I could sort of help