F 4.6 engine

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Hello everyone!

Got a brand new Savage X with the F 4.6 engine. However, the retaining pin disintegrated along with the wrist pins on my first one destroying the piston and sleeve. I bought a new F 4.6, broke in the engine, tuned it, and had no issues. The next day the engine would start but die when I gave it throttle. Messed with the carb setting and nothing. I even put it back to factory but issues persisted. I then noticed black oil coming from the exhaust which had a fishy odor so I took apart the engine to clean it. When i removed the piston, I noticed there was ALOT of play from the con rod. The pin was still in tact. After I put everything back, the engine still had issues when throttle was applied. I'm guessing the amount of play in the con rod is the culprit. This is the second F 4.6 with the same issue relating to the piston assembly.

A friend of mine is also awaiting a new piston and sleeve set and had the same issue.

Has anyone else had this issue; especially with the F 4.6? Been debating on getting a new motor but staying away from HPI. Does anyone recommend anything that's great for bashing and reliable? Willing to spend under $200.
Thanks!
 
If you can still find them, the LRP28/30/32 are all good long running engines.

Is the play in the con-rod side to side on the piston or is it actual play if you push/pull on the con-rod while holding the piston? They all move side to side quite a bit. The back plate/starter shaft/bearing keep the con-rod in place when the engine is put together. But, if your feeling actual play as you push/pull the con-rod, then yeah, that's usually not good.
 
If you can still find them, the LRP28/30/32 are all good long running engines.

Is the play in the con-rod side to side on the piston or is it actual play if you push/pull on the con-rod while holding the piston? They all move side to side quite a bit. The back plate/starter shaft/bearing keep the con-rod in place when the engine is put together. But, if your feeling actual play as you push/pull the con-rod, then yeah, that's usually not good.
Play is when I push and pull. There is some play from the rod when I twist it side to side. I attempted to run car after cleaning black oil and it simply would not run even with a little bit of throttle.
Regarding the LRP engine, is there anything in particular I need? Can I simply just install, break in, and run?
Thanks for the response!
 
Pretty much any .21 - .32 engine can be used without much hassle. Sometimes the exhaust port varies in size, but other than a new gasket for the exhaust, they are pretty universal. 99% sure I used the HPI purple one with my LRP28/30 in my savage with the HPI easy flow header and the normal savage header.
 
Pretty much any .21 - .32 engine can be used without much hassle. Sometimes the exhaust port varies in size, but other than a new gasket for the exhaust, they are pretty universal. 99% sure I used the HPI purple one with my LRP28/30 in my savage with the HPI easy flow header and the normal savage header.
I will definitely look into those engines. In regards to the push-pull play, what do you think caused it? I broke in the engines just like the manufacturer recommended and insured not to over lean the engine. Again this is the second time this problem happened.
 
I would like to see pictures of what has happened, it may help determine what went wrong......
 
I will definitely look into those engines. In regards to the push-pull play, what do you think caused it? I broke in the engines just like the manufacturer recommended and insured not to over lean the engine. Again this is the second time this problem happened.
Well, the "break-in" instructions in my opinion get you started. Many people do different styles of break-in. I heat cycle mine at about 1/2 tank intervals for the first 2-3 tanks. I lean it out a bit with half a tank in and keep leaning to get the temps up some. Usually by tank 3, I'm able to get to 200F. Then I just keep it running while adjusting the tune a bit to end up with a relatively clean exhaust note by the time I get to tank 5 or so.

For all tanks, I drive it slowly with slow throttle input up to 1/2-3/4 throttle and back off. A whole lot of 2-3 second acceleration cycles. Gradually increasing throttle up to 3/4 throttle and take about 2-3 seconds to do it., then back off to idle similarly, turn around and do it again. Over and over. Usually a minimum of 8 tanks (1/2 gallon) before I go WOT. Even then, I don't hit WOT very often for the first entire gallon.

That's for a big block. Small blocks burn through less fuel and are usually broken in enough to run solidly by the above around 1/2-3/4 gallon. Regardless, I'm very easy on my engines for the first 1 to 1.5 gallons. Very little extended WOT running in a field or anything. By gallon 2, I run them as hard as any engine.

Usually, the more expensive the engine, the longer it takes for it to wear itself in. Better materials, tighter tolerances, etc. Back in the day, the OS21RG's I ran were well broken in by 1/2-3/4 gallon. The SH and XTM engines were the same as were the dynamites. The LRP's didn't really wake up and tune solidly until I got over a gallon through it. The OS18Tm and OS21TM also took more fuel. The 21TM didn't wake up until 1.5 gallons or so. The 18TM (small block) didn't until about a gallon.

You may have started running it hard before it was ready to do so.

I never let an engine sit and idle much during break in. Many manuals say to let it idle through a tank or two... I do not.

The last engine I kept track of for fuel had 12 gallons on it when I sold it. I lost touch with the new owner around 15 gallons. He had to change carb o-rings as the o-rings dried up and were walking on him while it ran, but it was still a ripper the last time we met. That was an LRP28. I usually get rid of an engine before I get 10 gallons through it, but I've only had a couple (non traxxas) engines die on me early. One was from a bearing ball breaking in half, that was an OS21RG. The other was an OS21RG that the filter fell off at some point and sucked in a ton of silt throughout the day. I literally poured mud out of that engine. It still ran, but it would flame out due to lack of compression when hot. I've probably owned/broken in over 30 engines in the past 20 years.
 

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