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A guy I used to work with has a beautiful 66 tbird/390...rebuilt the motor(think it was using oil) last year, now its overheating. he pulled the motor back out again, said the guy that built it had too tight ring gap/friction overheating(but I kinda think if it had been tight it would have seized/galled the bores/etc...), anyways- put back in, overheating, pulled back out, replaced head gaskets thinking one may have been installed wrong or something, overheating still...two water pumps, triple core radiator etc...still overheating.
I just saw him two days ago and he told me what he'd done, and how much he'd spent(first time I'd talked to him since last year before he tore it down). He said that it dont overheat driving or cruising on the highway, but as soon as he slows down, it heats up- heavy radiator added, 7 blade fan added, still heating up. he said someone told him he had the wrong heads~castings were no good(original parts), I told him I couldnt see how heads could overheat at idle/but not at cruising speed...sounded like water pump/fan/radiator issue to me, but hes replaced all these things twice already. he started it up for me and within 30 seconds the temp was pegging out...maybe some kinda air 'bubble' trapped in the water jackets?
I really doubted a cracked block/head, or 'wrong heads' as his buddy told him could result in overheating at idle but not at cruise rpm- would hate to see him throw more money in the wrong direction...it sure sounds like its not pumping enough water to me- cant imagine radiator contents heating that rapidly at idle...sure sounds to me like his pump aint moving any coolant at idle- suggested he leave cap off to prevent pressure and put some clear tubing on one of his radiator hoses to *maybe* see if anything flowing. something else- he has looped the heater hoses as his heater core started leaking- that couldnt bypass enough at idle to starve a head or something could it?
Anyone got any ideas or heard of any such thing before? Really a shame as this car is a cherry original, perfect everywhere except for this overheating thing. that car has the coolest red leather interior ive ever seen...anyone thats got any advice please share and I'll pass it along.
 

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JAck up the front of the car as high as you can. This should let any trapped air get out.

IF the coolant wasnt flowing, it'd over heat at any speed. His is simply an airflow issue. Is there an A/C condensor or an oil cooler that wasnt there before? Is he running a shroud? Real easy one to overlook, but is the fan installed backwards? Are the fan blades pitched the right direction? I'd look at anything that could impede airflow before doing anything else. If that doesnt do it, Maybe he needs a smaller water pump pulley or larger crank pulley to get things moving faster at idle.
 

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Pull the thermostat and check water flow. There is also a dye you can use to see if there is any leakage from gaskets or craked block ect. Might be the time to drive it to the radiator shop (good & honest one) so they can add their own .02
 

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Another thing that is easily overlooked are radiator hoses. Could he have one collapsing, or partially collapsing? Even some new ones will do this, if they have no spring in them.

Ray
 

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Be sure to pressure test the system and see if it can hold 20+ psi pressure. If not, you'll see this problem too.
 

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Discussion Starter #8
On 2005-07-24 00:25, Luv70sFords wrote:
JAck up the front of the car as high as you can. This should let any trapped air get out.

IF the coolant wasnt flowing, it'd over heat at any speed. His is simply an airflow issue. Is there an A/C condensor or an oil cooler that wasnt there before? Is he running a shroud? Real easy one to overlook, but is the fan installed backwards? Are the fan blades pitched the right direction? I'd look at anything that could impede airflow before doing anything else. If that doesnt do it, Maybe he needs a smaller water pump pulley or larger crank pulley to get things moving faster at idle.
thanks for the replies guys-

will ask him if he tried this jacking up to get air out...

coolant must be flowing at cruise rpm- I did look at his fan, its running right direction(was wondering if 'marine' FE's with reverse rotation were ever built- heard long ago of a guy with a checy heating problem- had marine water pump with reverse impeller). fan was about 2" from radiator, thought it might benifit from longer spacer, but he said gap was same as original. * just rethinking, wondering if perhaps he got a pump that was rebuilt and impeller flipped? anyone out there know if this would even be possible?* Ive seen similar coolant pumps on machines running backwards but still pumping at very reduced flow...

I looked at his fan/shroud- he had a kinda homemade shroud which was more of just a 3 sided box that would help nothing...I mentioned without shroud being close to the fan it wouldnt help...he said he was getting a factory shroud this week, and if it didnt help was going to try an electric fan.
hopefully one or the other will help, but i still think hes got something else amiss in there...

Ive never rebuilt a water pump, so dunno if assembly error is possible, but ran into a rebuild error just a couple months ago on an alternator- case was spun 180, plugs woulda hit the block...Rebuilders hire new guys once in a while too

I'm curious on rebuilding FE pumps if impeller has to be pressed off the shaft to replace bearings/seals...he told me he put 2 new pumps on, but dunno if from same vendor or not- is there a way to look into the inlet/outlet to actually 'see' the impeller direction?

I was thinking a shroud would help, but if you would see how fast his temp gage shoots up at idle, I really think he's not getting any circulation at all at idle rpm- I cant imagine an idling motor heating the radiator contents in under 30 seconds- I mean after 10 seconds the temp starts to rise and fast. Sure hope he hasnt got clearance(assembly) issues, as he's never done any engine work before and is relying on others- first try somebody didnt like the ring gap so bought bigger rings, he had to have it tore down and swapped- guess it was so tight it wouldnt crank once it started to warm up.(heard of similar mess from a friend that cut/gapped oil 'expansion' springs to match oil scraper ring gap when rebuilding his brothers motor- probably sounds kinda funny to someone that knows better, man did that poor car smoke...I'd definitely call that learning the hard way)
 

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Here's what I've seen sometimes. When people rebuild engines they just knock the old core plugs in the block and leave them. Your's might still be in the block restricting flow. Seen that more times then not.
 

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Are there any bubbles in the coolant when its running?I'm just wondering if exhaust pressure is entering the cooling system somewhere(cracked head or block or bad gasket etc) which would explain why the coolant gets hot so quickly.
 

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There is NO WAY ON GOD'S GREEN EARTH, that an FE can start up from cold, and get to hot temp within 60 Seconds. PERIOD! I have run FE's W/O water for 2 minutes and never had the block get as hot as you're talking...

I just can't see it happening.... The gauge sounds to be working properly if it does not show hot while cruising highway speeds... But....

Do have him lift the front of the car when adding coolant though. I cannot think that too little tolerance on the ring gap causing this either, and if it were the Bearings being too tight they would have bveen thumping by now... They would have worn down to the copper already....

The major issue that I see is the Fan Shroud... He needs a proper one or the car WILL heat up in traffic or just sitting, although not nearly as fast as the gauge is protraying...

Keep us informed...


FEandGoingBroke
 

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Discussion Starter #13
On 2005-07-25 12:05, FEandGoingBroke wrote:
There is NO WAY ON GOD'S GREEN EARTH, that an FE can start up from cold, and get to hot temp within 60 Seconds. PERIOD! I have run FE's W/O water for 2 minutes and never had the block get as hot as you're talking...

I just can't see it happening.... The gauge sounds to be working properly if it does not show hot while cruising highway speeds... But....

Do have him lift the front of the car when adding coolant though. I cannot think that too little tolerance on the ring gap causing this either, and if it were the Bearings being too tight they would have bveen thumping by now... They would have worn down to the copper already....

The major issue that I see is the Fan Shroud... He needs a proper one or the car WILL heat up in traffic or just sitting, although not nearly as fast as the gauge is protraying...

Keep us informed...


FEandGoingBroke
I shoulda been more specific- car had only been sitting about 1/2 hour- gage(antique original) showed bottom end of 'normal- but rose VERY rapidly after starting- radiator felt only warm before starting, so dont think it was drawing in hot water- if I'd have been thinking shoulda felt radiator again after he shut it off...)
when I was talking to him it was pretty dark out- I dunno where sending unit is located- assuming from the rapid rise that it would HAVE to be submerged/near combustion chamber/little to no coolant flow. sounded like gage error too, but he said its fine at cruise...other thing I'm not sure of is what machining was done- obviously from him describing ring problem he musta had it bored, hopefully not too thin/dunno if he enlisted any 'porting' help either- even though I kinda think a casting that much too thin would have cracked by now...will probably run into him again saturday, will repeat suggestions for Dye checking/mech gage/jacking to remove bubbles/shroud...hopefully he'll already have figured something out, but as its been months/three teardowns already, I think it might be doubtful. Really a shame as its one of the nicest tbirds I've ever seen, and I'm sure he's thrown an awful lot of time and money away the past few months. will let you know- thanks again for all the tips guys!
 

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Temp unit is in the front on the intake manifold near the distributor. I also think you should get a manual ice pick guage start the car with the cap off and see just how fast it heats up. Something doesn't sound right.

<font size=-1>[ This Message was edited by: Rattpac on 7/26/05 11:56am ]</font>
 

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Was is the over-bore on his engine? He may have just gotten too thin. He may want to try an aluminum radiator also as a crutch, but there is something else going on. I wonder if he may have swapped pullies at some point?
 

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try a meat thermometer in the rad ,to see temp, and make sure rad cap,has proper pressue,but my 390 failane would run hot,after i took the shroud off, didn't pull enought air from corners,of rad, and if you turn heater on does the gauge drop. bill
 

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I have the EXACT same problem….plus lots of moolah involved.
Bought a fresh “422 HP” FE from Tuff Dawg engines of Arizona.
New Aluminum heads. Installed in my ’68 Cougar. From the instant
I started the engine (including the 15 minute break-in run) to this day…
200 miles later, it still is running
between 210’-220’. Frustrated, took to shop where my new Griffen
aluminum radiator was replaced with a MONSTER crossflow one
(so big, they had to move the battery to the trunk). Twin electric
fans with custom shroud also installed. Still running waaaay too hot.
Tuff Dawg suggests stock water pump instead of the high flow I put in.
Switch made…(anyone need a new Edelbrock aluminum hi flow water pump??
.Still no change. (see where the money pit is heading?)
Street Rods Plus of Lodi, CA. (shop I had try to figure this overheating issue
out) thinks maybe backward head gasket…not sure but frustrated also.
I did notice at one time while cruising, the temp dropped to about 190’
hmmmm. I wonder if the poster who says maybe old freeze plug may be
floating around inside the block has a point. At this point I guess I need to
pull engine (one year warranty from Tuff Dawg….hmmmm maybe have to
send it back to them…..more money)….maybe best to pull current freeze plugs out
and rotate on engine stand and hope something rattles around and is accessible to
take out….wish there was a simple solution….
 
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