RF93 Pinto cylinder head gasket/overheating/etc

[troyt]

Has anyone done any research why 7 of the 17 water jacket passages between the block and head are completely blocked by the gasket, while another 4 only have a tiny passage hole?

On other notes:
I've been chasing an overheating problem in my RF93 since I got it up and running last month. I had it out for a test and race wknd, and once I solved (or at least diminished) the oil leaks and electrical gremlins, I finally got some good laps in. Problem is it goes through about 3/4 gallon of water in 10 minutes of running, then starts to overheat. No signs of water leakage around radiators, water pump, or water inlet. Cooling system bled and radiator bleeds working properly. Radiators seem to warm up at the expected rate. No water in the oil. No signs of combustion contaminants in the water. Rad cap holds normal pressure, starts to bleed out steam/water when the system overheats.
Since I ran into the cyl head stud issue where you can't remove the head in situ, I just re-torqued the head bolts, tried improving the airflow across the radiators, and went back out last weekend, to the same results. Runs great for 3-4 laps, then overheats and water level is almost a gallon low.
Pulled the motor today expecting to see a bad head gasket or a crack in the head or bore. Nothing looks abnormal. Good gasket, no water trails between water jackets and combustion chamber, no visible cracks in the usual expected places. So where is my water going???

Also two other issues. One of the oil leaks appears to be the rear crank seal. Are they replaceable with the motor assembled?
Found a crack in the bellhousing starting at the starter mounting surface half way between two of the starter bolts, and traveling rearward a few inches. Plan to just clean it out and weld it up.

[Purple Frog]

First, are you installing the head gasket right side up?

Are you properly bleeding the air out of the system when you add the coolant? Could be your rads have air trapped in them.

And you do have a swirl pot mounted higher than the head, right?

I suspect your rads are clogged. Take them to a radiator shop and have them rodded out. They can be mostly clogged and still flow enough water to fool you.

You said you pressure tested the cap. Did you pressure test the assembled system? Could be a pin hole leak in a hose.

Rear main seal can be changed by removing the flywheel.

Fixing the crack is a major pain. Usually you have to totally disassemble the bellhousing and put it in an oven to cook out all the oil in the crack before it can be welded correctly.

[Rick Kirchner]

There's no swirl pot on the pre-97 VDs unless you fab one. If it has the plastic and aluminum rads there are no steam bleeds either. The parallel setup has a tendency to not work very well.

[troyt]

Thanks for the input/ideas, keep 'em coming...

-Head gasket was properly oriented upon disassembly.
-No swirl pot. The cylinder head water outlet feeds a junction "box" that has three "outlets". The top one is for the radiator cap/fill tube (this tube is where the bleed lines from the tops of both radiators feed into) and the bottom two feed the tubes to the tops of the radiators. You can watch the bleed lines operate after a major refill.
-Did not pressure test cooling system while assembled, should have.
-Rads will be removed and rodded.
-Water temp is measured at rear of block, thinking about moving sensor to a water outlet tube/radiator feed tube???
-Head will be pressure checked, heck maybe its time for an uprated cam while I'm at it...

Has anyone ever opened up the "closed off" water jacket holes in the head gasket?

Source for water pump hose? 1.25" out of rad outlet line and 1.5" into water pump with a 40 degree bend.

[gbilawsky]

Your issue sounds to be beyond these solutions, but they are worth adding to the list of items to investigate:

Are you running with a thermostat or restrictor plate in the cylinder head water outlet to slow down the rate of flow so the water has enough "radiator standing time" to cool? If you don't already have one, you might also look into an under drive pulley set to slow the water pump down to also allow more cooling time in the radiator.

[DaveW]

The closed holes are that way because if they were open, coolant would short-cut through them and parts of the head, especially at the rear, would not have enough coolant flow to be properly cooled. The rear of the head is usually where heating issues are first noticed even with the closed-off holes.

[Rick Kirchner]

The "slower cooling" thing probably won't fix this problem.

Troy - if there's no water in the catch tank and no evidence of a leak into the cylinder head (steam cleaned combustion chamber) then it's probably not getting filled.

To get an idea of the proper amount, get a big jug (I use a 3 gallon water cooler jug) and a big funnel. Fill the rads completely and dump in. Do the same with the piping, the head, and the block. Mark the jug and now you know how much to put in from dry.

The pre-98 VDs are very hard to get the correct level. The cap is not high enough. There's not enough room in the stock system to see that it's properly filled without filling it to the top. Then when the car gets hot it will push out a bunch into the puke tank. If you can fashion a recovery system it may help.

I took a pretty radical and costly approach to solving this problem. I bought radiators from Saldana from racing cores (the stock aluminum VD radiators have too high a fin density), made to the VD size but with top and bottom steam bleeds (so they can go on both sides of the car and so that they are easy to drain). The steam bleeds go to a header tank on the firewall that has the cap. The bottom of this tank feeds the pump through the heater inlet.

The pump has an impeller from Racemate. The hoses were all increased to 1.5" The system was converted to serial flow - the water comes out of the head and goes to the top of the left rad, out the bottom and into the bottom of the right rad, out the top there and into the bottom of the water pump. All the gaps around the radiators in the sidepod assemblies are plugged with high density foam.

This system runs reliably at 185 deg at Willow Springs or Buttonwillow when the temps are nearly 100 deg. I have to tape a radiator over completely in Feb and November.

I put the temp sensor in the hole at the front left of the head. It really reads head temp. If you put it in the water pipes and lose water it reads steam temp, which may lead to bigger problems, so if you do that you need to couple it with a water pressure sensor.

The water pump hose you are looking for is a standard pinto unit trimmed to fit if I remember correctly. You have to keep an eye on it because the proximity of the headers will cause it to harden and eventually fail.

[DaveW]

Your issue sounds to be beyond these solutions, but they are worth adding to the list of items to investigate:

Are you running with a thermostat or restrictor plate in the cylinder head water outlet to slow down the rate of flow so the water has enough "radiator standing time" to cool? If you don't already have one, you might also look into an under drive pulley set to slow the water pump down to also allow more cooling time in the radiator.

I don't want to sound contentious, but reducing the WP RPM is done to improve its efficiency and reduce its cavitation. Slowing the WP is not done to reduce coolant flow at racing RPM's.

Also, "slowing the coolant flow" will only degrade cooling. Higher coolant-flow speed gives more uniform coolant and head temperatures and improves cooling efficiency. What restricting the flow at the thermostat housing does to improve cooling is to raise the pressure in the head and minimize the amount of cavitation and localized boiling.

So there IS a benefit to exit restriction, but it is a balancing act between fast-enough coolant flow and having enough pressure in the head to eliminate localized boiling.

[DanW]

Troy,

When the time comes to do a cooling system test, I have a pressure tester you can use. PM or email me when its time.

Dan

[troyt]

Well, there is no restriction in the water outlet, suggested diameter of one?
The radiator fin density does look a bit extreme, first time I've seen this design before.
The serial reroute is an interesting idea versus the factory parallel, will ponder that one.
The water pump belt is pretty darn loose and of unknown age. It appears to have no tension adjustment available. Source for a new belt, and tension suggestions?

[DaveW]

Well, there is no restriction in the water outlet, suggested diameter of one?
The radiator fin density does look a bit extreme, first time I've seen this design before.
The serial reroute is an interesting idea versus the factory parallel, will ponder that one.
The water pump belt is pretty darn loose and of unknown age. It appears to have no tension adjustment available. Source for a new belt, and tension suggestions?

For a restrictor I would use a 180F thermostat with a couple of 3/16" bypass holes to get a small amount of circulation before it opens to stabilize the coolant temperature.

Thread on parallel vs sequential radiator plumbing:

http://www.apexspeed.com/forums/show...lel+sequential

[CGOffroad]

beltplace.com

I just replaced the water pump belt and the oil pump belt on my car. Fortunately, my old belts still had manufacturer name and length/teeth numbers that were legible. I confirmed the length by measure and counted all the teeth. Did a search on BeltPlace and found different manufacturer names, but in the description it said 'replaces such-n-such' belt, which were my original belt id's.

They took PayPal and the belts were at my house in 2 or 3 days without paying expedited shipping. $21.69 total. Hard to beat!

[CGOffroad]

I put the temp sensor in the hole at the front left of the head. It really reads head temp. If you put it in the water pipes and lose water it reads steam temp, which may lead to bigger problems, so if you do that you need to couple it with a water pressure sensor

Rick, Do you have a photo of temp probe in the head? Is it a sensor that is part of a data acquisition system, or stand alone temp unit?

[troyt]

Well sometimes it's good to walk away and come back later, after a few good Apex searches of course...
Now that all the residual gunk has dried up overnight, it is obvious that the #2 cylinder has been getting steam cleaned. Couldn't see that yesterday with everything freshly disassembled. The other three holes have a light oil sheen, #2 has a dry grayish coating. Got the head gasket under closer inspection, you can see rust discoloration in it between the left side water jackets and the bore on the head side, block side is clean. Head also shows slight discoloration in same area, missed it yesterday...

Refresh the head, replace rear crank seal, rod the rads, some fresh hoses, wait for March...

[Rick Kirchner]

between the Dizzy and #1 intake:

[BeerBudgetRacing]

Cheater! Water injection is not allowed

Hopefully no damage to the cyl. From lack of oil..

[troyt]

Thanks to CGO's reply to my belt source question, I found the website, the correct address is:
http://beltpalace.com

Thanks for the pic, Rick. That's a good idea for sensor position. Since mine is on lower right rear, it goes by the headers which I don't like.

Also found a reinforced 1.5" to 1.25" reducer elbow in reinforced silicone by HPS for the water pump hose. The stock hose has a 40 degree angle while this one is 45, but close enough. #HTSER45-125-150-BLUE

When buying seals/gaskets, what year Pinto 2.0L is correct for ordering?

[Purple Frog]

Only because i've seen it happen...

The impeller on the waterpump gets loose on the shaft. I don't think that is your issue because you thought the rads were heating correctly.

My water pumps were always driven by cog-tooth belts. Slipping was not an issue.

I'm still suspect of the rads being clogged.

[troyt]

So why is a FelPro 2.0 Pinto rear crank seal $5, but through Pegasus it's $50?

[DanW]

So why is a FelPro 2.0 Pinto rear crank seal $5, but through Pegasus it's $50?

We cheat the other guy and pass the savings on to you!

[xmazdatracy]

So why is a FelPro 2.0 Pinto rear crank seal $5, but through Pegasus it's $50?

Saw that with their Hella Kill switch too.

[BruceRace]

Nice intake porting....is that legal?

[Purple Frog]

Porting is "free" on the pinto.
The intake manifold can be ported only to the extent that you can't break out of the outside casting.

[HayesCages]

Water restrictor has been mentioned...I think the VD water neck has it built in: it is 1" ID where it meets the head. (corrected size in post below)

Have you blown out the air bleed hoses that run from the rads. to the filler? I have seen them plugged with RTV silicone pieces and mechanic's glove parts...

[troyt]

Lawrence,
Good call on blowing out the bleed lines. I know at least one is working as I can see the bubbles bleed out after a refill, but I don't know if BOTH lines are working...

The VD water outlet neck/tube is 1 3/4". I'm thinking of putting in a fresh 180F thermostat with a couple drilled bypass holes. That's been my technique for years.

[HayesCages]

The ones we've made have a smaller, 1.180" hole in them.

[BeerBudgetRacing]

Porting is "free" on the pinto.
The intake manifold can be ported only to the extent that you can't break out of the outside casting.

PF, can you clarify? Since there was only a picture of the head....

GCR 9.1.1 15(e) says:

It is permissible to reshape inlet and exhaust port by removal of
metal within limits. Addition of material in any form is prohibited.
Maximum diameter of inlet port at manifold head face 39.5mm.
Maximum dimensions of exhaust port at manifold face 35.5mm x
27mm. The distance between the valve centers and the angles of
the valves shall not be altered.

[troyt]

Follow-up post: Good call by Lawrence, while one of my radiator bleed lines was clear, the other was clogged! So the bubbles I was seeing during bleeding was just from one side.

[troyt]

<<Found a crack in the bellhousing ... traveling rearward a few inches. Plan to just clean it out and weld it up.>>

<<Fixing the crack is a major pain. Usually you have to totally disassemble the bellhousing and put it in an oven to cook out all the oil in the crack before it can be welded correctly.>>

The bellhousing crack around one of the starter bolts ended up being pretty deep. I took a small cutting disc on a dremel and started cutting out the crack, and I finally got to the bottom of it, but deeper than I expected. Taking good advice, we ground out a big chunk, hot-tanked the disassembled housing, TIGed up the damage, and machined the mounting surfaces leaving as much of the weld as possible. Looks like it oughta hold up...

[a. pettipas]

Your rads are likely ancient history - unless you know for sure otherwise - do yourself a favour and buy new ones, they are not that expensive, eliminates an important variable. I wouldn't have the current ones cleaned if they look obviously long in the tooth, IMO not worth f*****g around with considering the ambient temps you experience out there in the summer.

[troyt]

Thanks Aaron. One radiator replaced, one cleaned. Testing continues ;-)

[Nardi]

Also make sure you can see thru the rad fins. If you can't, air won't pass thru.