JON242

Are you sure your guage is accurate? It seems like the increase from idle to running at speed is about right, just high across the range. You also might want to call GIL to see if they have any input. Maybe too much water going directly to the manifolds instead of through the block.

ursus

Yes make sure the sender on the new engine matches the guage brand/range.

there are many sender types 240-33 ohm is US standard, 10-180 ohms VDO, 180-10 ohms VDO and some others, there are also 220f senders 250f sender and 300f Oil temp sender altho that would read a low temp not high

Do you have the sender from the original engine ?

mcollinstn

Lots of folks suspecting blockage. Me too.

If you lost an impeller at some time, there might be pieces of it stuck in a line somewhere.

BAD-HABIT

It dosen't take much to toast an Alpha impeller. If it got hot just once you probally have damaged the impeller. Gotta be blockage or impeller or both. I had a partial blockage that toasted the impeller. Most mechanics replace the impeller EVERY year...Good luck let us what you find.

"Bad-Habit"

Iggy

My Formula has an Alpha drive and running on borrowed time with the impeller.
A while back I was contemplating switching to an engine mounted water pump, Bravo type, since somewhere along the way I want to change drives and a transom mounted pick-up.
People that have Alpha SS's use the belt driven pump with an external pick-up.
One of the board members said I could do it, no problem but I still have to have the old drive impeller operating because it helps cool the drive oil too and the drive may over heat without it. He then suggested I could use the drive pump to supply a drive shower.
I like that idea. Maybe you could do that too.

Havasu Hangin

Where is your sending unit, on the intake or the new heads?

jr

Iggy I use an external pickup that goes straight to the water pump in the Alpha SS. Works great and is kinda cool looking. I'm running stock 260 alpha type cooling and running 160 solid.

21_senza, when you built the engine did you have the block, manifolds and risers hot tanked?

Preuni

Had a similar problem with exactly the same set up, 383 Alpha 1 Gen 1...turned out to be the t-stat, didnt open completely.
Drilled three 3mm holes in T-Stat to get the hot water as well on the upper part of the T-stast, now it opens fully....140 degrees solid !
Good luck!
Andy

21_senza_383_2

You guys have come up with some good info here...Try to answer what I can-

First of all, I built the engine from a 1990 4-bolt truck block, very clean internals, and yes, block was hot-tanked (intake manifold & heads new). When I opened up my 1989 I/O block, one look inside the water passages and I decided that a partially prepped 4-bolt available at a machine shop for $250 looked pretty good. Especially after considering it was already hot-tanked, magnafluxed, pressure-tested, freeze plugs, cam bearings, tapped holes cleaned out, and bored .030".

Sending unit & T-stat housing came off the old engine (found that NAPA gave me the wrong size thread sending unit at the last minute, so had to re-use old one for now). I cleaned out the passages on the housing & replaced T-stat before reinstalling. Never had a temp issue before the new engine with this same sending unit.

I never "lost" the impeller. Should be no foreign objects in the system, but I will have to go searching for some kind of blockage.

3 holes x 3mm in the T-stat? That's a new one to me. Never heard of that before. Maybe while I'm digging around, I'll submerge half the T-stat & check that way (tried orig. T-stat in engine after checking fully submerged in hot water, and it was opening fine fully submerged (but still overheating).

You guys are a big help. Thanks for the input. Hopefully after my wife gets done dragging me up to Niagara Falls this weekend (all that water and nowhere to get on plane...what a waste!), I can do some searching Sunday night.

I'll post again when I know more, probably early next week.

cuda

Hey Iggy, the alpha I bought earlier this year didn't have an impeller in it at all. Someone must have had a pulley driven pump. It also had the nosecone. I am glad my mech decided to check the impeller before I ran it with no cooling at all. I asked him how they did it without the pump, because I was thinking the same as you, heat in the drive itself. He said the water line is just a drop in the bucket compared to all the water circulating around the outside of the drive. I have closed cooling on my 355/ alpha, and I have heard of people having cooling problems when the water gets as warm as it is now.